Archive for the ‘PostgreSQL DBA’ tag
PostgreSQL Calling File
Somebody asked: How do you run a script file from PostgreSQL’s psql prompt? I created two files to answer the question. Here are the two files:
Static File
SELECT 'Hello World!'; |
Dynamic File
SELECT 'Hello ['||current_user||']!'; |
It’s a simple solution, you put a \i or \include before the script file name, like:
\i helloworld.sql |
It outputs:
?column? -------------- Hello World! |
or
\include hellowhom.sql |
It outputs:
?column? ------------------ Hello [student]! |
I hope this helps those trying to call SQL script files from an interactive psql session.
PostgreSQL Identity Columns
It’s interesting to see the way different databases implement automatic numbering. Oracle Database 12c is the closest to PostgreSQL in some significant ways. However, its probably more accurate to say Oracle Database 12c copied PostgreSQL’s implementation. At least, that’s my conjecture because Oracle added a way to reset the START WITH value of the indirect sequence. However, I prefer the MySQL approach because the automatic numbering sequence is a property of the table and a simple clause of the CREATE TABLE statement.
Both PostgreSQL and Oracle Database 12c implement automatic numbering as indirect sequences. Indirect sequences are those created by a table when you designate a column as an identity column in Oracle or as a serial column in PostgreSQL. The difference is that PostgreSQL doesn’t provide a syntax version inside the CREATE TABLE semantic.
MySQL provides such syntax. You set an auto numbering column in MySQL by appending the AUTO_INCREMENT clause to the table creation statement when you want it to start with a number other than 1, like this:
CREATE TABLE auto ( id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT , text_field VARCHAR(30) NOT NULL ) ENGINE=InnoDB AUTO_INCREMENT=1001 DEFAULT CHARSET=utf8; |
Oracle disallows you to changing a sequence created as a background activity of the CREATE TABLE statement; and Oracle disallows you dropping an indirect sequence without changing the table that created it, which is exactly how they handle indexes created for unique constraints. Unfortunately, Oracle also disallows altering the START WITH value of any sequence.
If you want to change the START WITH value on an Oracle Database 12c indirect sequence, you must export the table, drop the table, and recreate the table with a new START WITH value before importing the data back into the table. The syntax for setting an IDENTITY column value higher than 1 is:
CREATE TABLE auto ( auto_id NUMBER GENERATED BY DEFAULT AS IDENTITY (START WITH 1001) , text_field VARCHAR2(30) , CONSTRAINT auto_pk PRIMARY KEY (auto_id)); |
You can only create a PostgreSQL table with automatic numbering by using the SERIAL data type, which always sets the initial value to 1. You can reset the SERIAL sequence value in PostgreSQL with the ALTER statement. Unlike Oracle Database 12c, PostgreSQL does let you modify the START WITH value of any sequence. The trick is understanding how to find the sequence name. The name is always the combination of the table name, an underscore, an id string, an underscore, and a seq string. This behavior makes a great case for choosing id as the name of any auto numbering columns in a table.
CREATE TABLE auto ( id SERIAL CONSTRAINT auto_pk PRIMARY KEY , text_field VARCHAR(30)); ALTER SEQUENCE auto_id_seq RESTART WITH 1001; |
You can see the table and assigned sequence with the following command in PostgreSQL:
\d+ auto |
It should display:
Table "public.auto"
Column | Type | Modifiers | Storage | Stats target | Description
------------+-----------------------+---------------------------------------------------+----------+--------------+-------------
id | integer | not null default nextval('auto_id_seq'::regclass) | plain | |
text_field | character varying(30) | | extended | |
Indexes:
"auto_pk" PRIMARY KEY, btree (id)
Has OIDs: no |
As always, I hope this helps those trying to sort through how to start identity columns above the initial value of 1.
PostgreSQL Composites
PostgreSQL like Oracle supports record data types but unlike Oracle, PostgreSQL doesn’t support collections of record data types. Here’s an example of how to define a PostgreSQL composite data type, and how to use it as a column’s data type.
CREATE TYPE address_type AS ( street_address VARCHAR , city VARCHAR , state VARCHAR , zip_code VARCHAR ); |
Then, you define an ADDRESS table, like:
CREATE TABLE address ( address_id SERIAL , address_struct ADDRESS_TYPE ); |
You can now insert rows like:
-- Insert the first row. INSERT INTO address ( address_struct ) VALUES (('52 Hubble Street','Lexington','KY','40511-1225')); -- Insert the second row. INSERT INTO address ( address_struct ) VALUES (('54 Hubble Street','Lexington','KY','40511-1225')); |
Then, you can query them like this:
SELECT * FROM address; |
It returns:
address_id | address_struct
------------+----------------------------------------------
1 | ("52 Hubble Street",Lexington,KY,40511-1225)
2 | ("54 Hubble Street",Lexington,KY,40511-1225)
(2 rows) |
You must use parentheses around the ADDRESS_STRUCT column to query individual items, like:
SELECT address_id , (address_struct).street_address , (address_struct).city , (address_struct).state , (address_struct).zip_code FROM address; |
It returns output like a table:
address_id | street_address | city | state | zip_code
------------+------------------+-----------+-------+------------
1 | 52 Hubble Street | Lexington | KY | 40511-1225
2 | 54 Hubble Street | Lexington | KY | 40511-1225
(2 rows) |
While you can define a table that holds an array of a composite type, there’s no syntax that appears to work with an array of a composite type. I hope this helps those interested in implementing record structures in PostgreSQL.
PostgreSQL Auto IDs
PostgreSQL’s approach to automatic numbering is as simple as Oracle but different than MySQL, and Microsoft SQL Server. For example, you have a two-step process with Oracle, PostgreSQL, MySQL, and Microsoft SQL Server. First, you create an Oracle table with the GENERATED AS IDENTITY clause, a PostgreSQL table with the SERIAL data type, a MySQL table with the AUTO_INCREMENT clause, and a Microsoft SQL Server table with the IDENTITY(1,1) clause. Then, you need to write an INSERT statement for Oracle, MySQL, or Microsoft SQL Server like:
- Oracle’s
INSERTstatement excludes the auto-incrementing column from the list of columns or provides aNULLvalue in theVALUES-list. You can then assign theRETURNING INTOresult from anINSERTstatement to a session-level (bind) variable. - MySQL’s
INSERTstatement excludes the auto-incrementing column from the list of columns or provides aNULLvalue in theVALUES-list. You can then assign theLAST_INSERT_ID()function value to a session-level variable, and populate a foreign key column. - Microsoft SQL Server’s
INSERTstatement excludes the auto-incrementing column from the list of columns or provides aNULLvalue in theVALUES-list. You can then assign theSCOPE_IDENTITY()function’s value to a session-level variable, and populate a foreign key column.
PostgreSQL differs because it works differently between the SQL and PL/pgSQL contexts. Let’s look at how you link the insert of data into two tables in both contexts.
The following PostgreSQL syntax creates an ADDRESS table with an auto incrementing ADDRESS_ID column that uses a SERIAL data type, which acts like an auto numbering column:
/* Create a customer table. */ CREATE TABLE customer ( customer_id SERIAL CONSTRAINT customer_pk PRIMARY KEY , first_name VARCHAR(20) , last_name VARCHAR(20)); /* Create an address table. */ CREATE TABLE address ( address_id SERIAL CONSTRAINT address_pk PRIMARY KEY , customer_id INTEGER , street_address VARCHAR(40) , city VARCHAR(30) , state VARCHAR(8) , zip_code VARCHAR(10)); |
If you want to insert one row into the CUSTOMER table and a related row in the ADDRESS table. You have two possible approaches. One works in both the SQL and PL/pgSQL contexts. That mechanism requires you to use a scalar subquery to capture the foreign key value of the CUSTOMER_ID column in the ADDRESS table, like this:
/* Insert into customer table. */ INSERT INTO customer ( first_name, last_name ) VALUES ('F. Scott','Fitzgerald'); /* Insert into address table. */ INSERT INTO address ( customer_id , street_address , city , state , zip_code ) VALUES ((SELECT customer_id FROM customer WHERE first_name = 'F. Scott' AND last_name = 'Fitzgerald') ,'599 Summit Avenue' ,'St. Paul' ,'Minnesota' ,'55102'); |
The RETURNING INTO clause of PostgreSQL only works in a PL/pgSQL context, like this:
DO $$ DECLARE lv_customer_id INTEGER; BEGIN /* Insert into customer table. */ INSERT INTO customer ( first_name, last_name ) VALUES ('Madeleine','Smith') RETURNING customer_id INTO lv_customer_id; /* Insert into address table. */ INSERT INTO address ( customer_id , street_address , city , state , zip_code ) VALUES ( lv_customer_id ,'7 Blythswood Square' ,'Glasgow' ,'Scotland' ,'G2 4BG'); /* Manage any exceptions. */ EXCEPTION WHEN OTHERS THEN RAISE NOTICE '% %', SQLERRM, SQLSTATE; END$$; |
You query the auto generated values and data from the INSERT statement to the CUSTOMER table with a scalar subquery against the natural key (the FIRST_NAME and LAST_NAME columns) from the ADDRESS table. The following is an example of such a query:
SELECT * FROM customer c INNER JOIN address a ON c.customer_id = a.customer_id; |
It returns:
customer_id | first_name | last_name | address_id | customer_id | street_address | city | state | zip_code
-------------+------------+------------+------------+-------------+---------------------+----------+-----------+----------
1 | F. Scott | Fitzgerald | 1 | 1 | 599 Summit Avenue | St. Paul | Minnesota | 55102
2 | Madeleine | Smith | 2 | 2 | 7 Blythswood Square | Glasgow | Scotland | G2 4BG
(2 rows) |
My take is that the RETURNING column_value INTO local_value clause is a better approach than using Oracle’s .NEXTVAL and .CURRVAL values. I also think the RETURNING INTO clause is a better approach than using MySQL’s LAST_INSERT_ID() or Microsoft SQL Server’s SCOPE_IDENTITY().
Initially, I felt it was odd that the PostgreSQL disallows the RETURNING INTO clause in a SQL context, because it allows the syntax in a PL/pgSQL context. After some reflection the choice makes more sense because most developers work within a procedural context when they use transactions across two or more tables. PL/pgSQL is PostgreSQL’s procedural context from managing transactions across two or more tables.
As always, I hope this helps.
A PL/pgSQL Function
Somebody wanted to know how to write a basic PostgreSQL PL/pgSQL function that returned a full name whether or not the middle name was provided. That’s pretty simple. There are principally two ways to write that type of concatenation function. One uses formal parameter names and the other uses positional values in lieu of the formal parameter names.
The two ways enjoy two techniques (SQL language and PL/pgSQL language), which gives us four possible solutions. I’ve also provided a conditional drop statement for the full_name function. If you’re new to PostgreSQL the DROP statement might make you scratch your head because you’re wondering why you need to use the formal parameter list. The DROP statement needs the parameter list because PostgeSQL lets you overload schema/database functions and procedures.
The code is for a named parameter lists using the SQL language is:
DROP FUNCTION IF EXISTS full_name ( IN pv_first_name text , IN pv_middle_name text , IN pv_full_name text); CREATE FUNCTION full_name ( IN pv_first_name text , IN pv_middle_name text , IN pv_last_name text , OUT pv_full_name text) AS 'SELECT pv_first_name || CASE WHEN pv_middle_name IS NOT NULL THEN '' '' || pv_middle_name || '' '' ELSE '' '' END || pv_last_name' LANGUAGE SQL; |
The code is for a positional parameter lists using the SQL language is:
DROP FUNCTION IF EXISTS full_name ( IN text , IN text , IN text); CREATE FUNCTION full_name ( IN text , IN text , IN text , OUT text) AS 'SELECT $1 || CASE WHEN $2 IS NOT NULL THEN '' '' || $2 || '' '' ELSE '' '' END || $3' LANGUAGE SQL; |
You would re-write the function in the PL/pgSQL language as follows (please note the named parameter list):
CREATE FUNCTION full_name ( IN pv_first_name text , IN pv_middle_name text , IN pv_last_name text) RETURNS text AS $$ DECLARE lv_output text; BEGIN IF pv_middle_name IS NULL THEN lv_output = CONCAT(pv_first_name, N' ', pv_last_name); ELSE lv_output = CONCAT(pv_first_name, N' ', pv_middle_name, N' ', pv_first_name); END IF; RETURN lv_output; END $$ LANGUAGE plpgsql IMMUTABLE; |
You can test either version of the program with the following two queries from the pseudo table dual, which isn’t require in the SELECT statement:
SELECT full_name('Henry',NULL,'Pym') AS "Ant-Man" UNION ALL SELECT full_name('Henry','''Hank''','Pym') AS "Ant-Man"; |
It prints:
Ant-Man text ---------------- Henry Pym Henry 'Hank' Pym |
As always, I hope this helps those looking for how to accomplish a concatenation function in PostgreSQL.
Fedora PostgreSQL Install
Somebody asked how to put PostgreSQL on my Fedora image with Oracle Database 11g and MySQL. It’s fairly simple. You can check for the current download at yum.postgresql.org and then download it like this as the root user:
yum localinstall http://yum.postgresql.org/9.3/fedora/fedora-20-x86_64/pgdg-fedora93-9.3-1.noarch.rpm |
You should see the following output when the download is successful, don’t forget to type y to complete the download:
Loaded plugins: langpacks, refresh-packagekit pgdg-fedora93-9.3-1.noarch.rpm | 5.1 kB 00:00 Examining /var/tmp/yum-root-2EPf_J/pgdg-fedora93-9.3-1.noarch.rpm: pgdg-fedora93-9.3-1.noarch Marking /var/tmp/yum-root-2EPf_J/pgdg-fedora93-9.3-1.noarch.rpm to be installed Resolving Dependencies --> Running transaction check ---> Package pgdg-fedora93.noarch 0:9.3-1 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: pgdg-fedora93 noarch 9.3-1 /pgdg-fedora93-9.3-1.noarch 2.1 k Transaction Summary ================================================================================ Install 1 Package Total size: 2.1 k Installed size: 2.1 k Is this ok [y/d/N]: y Downloading packages: Running transaction check Running transaction test Transaction test succeeded Running transaction (shutdown inhibited) Installing : pgdg-fedora93-9.3-1.noarch 1/1 Verifying : pgdg-fedora93-9.3-1.noarch 1/1 Installed: pgdg-fedora93.noarch 0:9.3-1 Complete! |
After downloading the packages, you install with the following command:
yum install postgresql93-server |
You should see the following output when the installation is successful, don’t forget to type y to complete the installation:
Loaded plugins: langpacks, refresh-packagekit pgdg93 | 3.6 kB 00:00 (1/2): pgdg93/20/x86_64/group_gz | 332 B 00:00 (2/2): pgdg93/20/x86_64/primary_db | 84 kB 00:00 Resolving Dependencies --> Running transaction check ---> Package postgresql93-server.x86_64 0:9.3.5-1PGDG.f20 will be installed --> Processing Dependency: postgresql93-libs(x86-64) = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64 --> Processing Dependency: postgresql93(x86-64) = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64 --> Processing Dependency: postgresql93 = 9.3.5-1PGDG.f20 for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64 --> Processing Dependency: libpq.so.5()(64bit) for package: postgresql93-server-9.3.5-1PGDG.f20.x86_64 --> Running transaction check ---> Package postgresql93.x86_64 0:9.3.5-1PGDG.f20 will be installed ---> Package postgresql93-libs.x86_64 0:9.3.5-1PGDG.f20 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: postgresql93-server x86_64 9.3.5-1PGDG.f20 pgdg93 3.6 M Installing for dependencies: postgresql93 x86_64 9.3.5-1PGDG.f20 pgdg93 1.0 M postgresql93-libs x86_64 9.3.5-1PGDG.f20 pgdg93 203 k Transaction Summary ================================================================================ Install 1 Package (+2 Dependent packages) Total download size: 4.8 M Installed size: 22 M Is this ok [y/d/N]: y Downloading packages: (1/3): postgresql93-libs-9.3.5-1PGDG.f20.x86_64.rpm | 203 kB 00:00 (2/3): postgresql93-9.3.5-1PGDG.f20.x86_64.rpm | 1.0 MB 00:01 (3/3): postgresql93-server-9.3.5-1PGDG.f20.x86_64.rpm | 3.6 MB 00:02 -------------------------------------------------------------------------------- Total 1.6 MB/s | 4.8 MB 00:02 Running transaction check Running transaction test Transaction test succeeded Running transaction (shutdown inhibited) Installing : postgresql93-libs-9.3.5-1PGDG.f20.x86_64 1/3 Installing : postgresql93-9.3.5-1PGDG.f20.x86_64 2/3 Installing : postgresql93-server-9.3.5-1PGDG.f20.x86_64 3/3 Verifying : postgresql93-server-9.3.5-1PGDG.f20.x86_64 1/3 Verifying : postgresql93-9.3.5-1PGDG.f20.x86_64 2/3 Verifying : postgresql93-libs-9.3.5-1PGDG.f20.x86_64 3/3 Installed: postgresql93-server.x86_64 0:9.3.5-1PGDG.f20 Dependency Installed: postgresql93.x86_64 0:9.3.5-1PGDG.f20 postgresql93-libs.x86_64 0:9.3.5-1PGDG.f20 Complete! |
You can confirm the installation with the following command:
rpm -qa | grep postgres |
It returns:
postgresql93-9.3.5-1PGDG.f20.x86_64 postgresql93-server-9.3.5-1PGDG.f20.x86_64 postgresql93-libs-9.3.5-1PGDG.f20.x86_64 |
You’ve now installed PostgreSQL but did you really? If you’re asking that questions you have other questions. Let me try to answer them quickly, here:
You have installed PostgreSQL and created a postgres user. postgres is the owner of the PostgreSQL database. You can connect to the database as the postgres user without credentials because that’s where you administer the database. However, you can’t connect using ssh as the postgres user. You must use sudo to assume the root user’s privileges and then use the su command to become the postgres user.
If you just completed the installation, you are the root user. You can verify that with a call to the whoami utility:
whoami |
It should return:
root |
You connect as the postgres user with the su utility like this:
su - postgres |
If you rerun the whoami command now, you should see:
postgres |
You can start the PostgreSQL command-line utility (psql), like this:
psql |
At the postgres (or psql) prompt, you can interactively confirm the setup of a database installation:
postgres=# SELECT setting as "Data Location" postgres-# FROM pg_settings postgres-# WHERE name = 'data_directory'; |
It should return the following:
Data Location ------------------------- /var/lib/pgsql/9.3/data (1 row) |
At this point, you should refer to this other blog post that shows you how to setup a new Database or Schema in PostgreSQL. You can find basic Postgres help files in this other blog post. As always, I hope this helps those timid about adding new software.
PostgreSQL New Database
How time flies, last March I explained how to install and configure PostgreSQL on Windows. It was my intent to start posting more content on PostgreSQL but I was distracted by another writing commitment on Oracle Database 12c PL/SQL Advanced Programming Techniques, which should be available in November. It tempted me away from PostgreSQL because I got to write about how to use Java inside Oracle Database 12c, which was fun. Having completed that, I’m back on task. Here’s the second entry on PostgreSQL. It shows you howto create your own database, database administrator role, user, and how to connect with psql CLI (Command Line Interface) as the new user.
- Create a user-defined
video_dbtablespace for your database. This requires that you know where the physical files where created when you installed PostgreSQL. You can discover the directory with the following query:
SELECT setting AS "Data Location" FROM pg_settings WHERE name = 'data_directory'; |
Data Location -------------------------------------- C:/Program Files/PostgreSQL/9.3/data (1 row) |
You create the video_db tablespace with the following syntax:
CREATE TABLESPACE video_db OWNER postgres LOCATION 'C:\Program Files\PostgreSQL\9.3\data'; |
You can check the presence of the video_db tablespace after creating it with the following query:
SELECT * FROM pg_tablespace; |
It should print:
spcname | spcowner | spcacl | spcoptions ------------+----------+--------+------------ pg_default | 10 | | pg_global | 10 | | video_db | 10 | | (3 rows) |
It’s important to note for those new to PostgreSQL that the pg_global and pg_default tablespaces are creating when initializing the database. The pg_global holds shared tables and the pg_default holds everything else.
- Create a database that uses your user-defined
video_dbtablespace with the following two commands:
CREATE DATABASE videodb WITH OWNER = postgres ENCODING = 'UTF8' TABLESPACE = video_db LC_COLLATE = 'English_United States.1252' LC_CTYPE = 'English_United States.1252' CONNECTION LIMIT = -1; COMMENT ON DATABASE videodb IS 'VideoDB'; |
- Create a database role, grant the super user privileges to the role, and create a user with the role. You can do that with the following three commands:
CREATE ROLE dba WITH SUPERUSER; GRANT ALL PRIVILEGES ON DATABASE videodb TO dba; CREATE USER video WITH ROLE dba PASSWORD 'video'; |
- Connect to the new
videodbdatabase with thepsqlCLI as thevideouser. You can do that with the following OS command:
psql -d videodb -U video |
- Once connected as the new
videouser, you can use a system information function to determine the current database:
SELECT current_database(); |
It should display:
current_database ------------------ videodb (1 row) |
There are many privilege options, and you should choose wisely which ones you use. As always, I hope this answers questions for other users.
PostgreSQL Install-Windows
A number of folks have asked me to create a post of a PostgreSQL installation on Windows. So, here is my step-by-step PostgreSQL 9.3 installation, and you can go further and learn how to setup your own PostgreSQL database schema.
Download PostgreSQL Database
You can start the download of PostgreSQL from this site. It leads you to the EnterpriseDB site, where you can download the prepackaged software.
Install PostgreSQL 9.3 on Windows
These steps walk you through installing PostgreSQL and the the pgJDBC v9.3, psqlODBC (32 bit), and psqlODBC (64 bit) packages.
- The first thing you need to do is launch the PostgreSQL file from download folder.
- After launching the downloaded file, you see an Open File – Security Warning dialog message. Click the Run button to run the PostgreSQL executable file.
- The first dialog screen is the Setup – PostgreSQL dialog, which welcomes you and prompts you to start the installtion of PostgreSQL. Click the Next button to continue.
- The Installation Directory dialog sets the location for the PostgreSQL server. Click the Next button to continue.
- The Data Directory dialog sets the location for the PostgreSQL server’s data repository. Click the Next button to continue.
- The first Setup dialog sets the database’s superuser password. Click the Next button to continue.
- The second Setup dialog sets the database’s listener port, which is Port
5432by default. Click the Next button to continue.
- The third Setup dialog sets the database’s default Locale. Click the Next button to continue.
- The Ready to Install dialog lets you start the installation. Click the Next button to continue.
- The Installing dialog lets you montor the unpacking of programs for the installation. You need not click any buttons to continue.
- The Completing the PostgreSQL Setup Wizard dialog advises you that you’ve completed the setup. Checking the Stack Builder check box lets you download and install additional tools, drivers, and applications. Click the Next button to continue.
- This is Welcome dialog to the Stack Builder. Click the Next button to continue.
- This is dialog lets you select applications that you would like to install. Click the plus symbol for the Database Drivers option to continue.
- In the modified dialog, click the pgJDBC v9.3, psqlODBC (32 bit), and psqlODBC (64 bit) check boxes. Then, click the Next button to continue.
- This dialog tells you the pgJDBC v9.3, psqlODBC (32 bit), and psqlODBC (64 bit) installed packages. Click the Next button to continue.
- This dialog lays a downloading progress bar while loading the additional packages. You don’t need to do anything to continue.
- This dialog lays a downloading progress bar while loading the additional packages. Click the Next button to continue.
- The Setup pgJDBC dialog welcomes you to the setup wizard. Click the Next button to continue.
- The Installation Directory dialog lets you set the pgJDBC installation directory. Click the Next button to continue.
- The Ready to Install dialog lets you install the pgJDBC package. Click the Next button to install it.
- The Setup dialog confirms you’ve installed the add-on packages. Click the Finish button to complete the installation.
Configure psqlODBC on Windows
These steps walk you through configuring the psqlODBC packages.
- The Setup dialog helps you configure the psqlODBC package. Click the Next button to install it.
- The Installation Directory dialog lets you set the psqlODBC installation directory. Click the Next button to continue.
- The Ready to Install dialog lets you install the psqlODBC package. Click the Next button to install it.
- The Ready to Install dialog lets you install the psqlODBC package. Click the Next button to install it.
- The Installing psqlODBC dialog displays a dialog while installing the psqlODBC package(s). You need not click anything, the dialog dismisses itself when complete.
- The Installing psqlODBC dialog displays a dialog while installing the psqlODBC package(s). You need not click anything, the dialog dismisses itself when complete.
- The Stack Builder dialog displays a message that everything is installed. Click the Finish button when complete.
Connect to the Default PostgreSQL database
You have two options for connecting to the PostgreSQL database. One uses the GUI pgAdmin III console and the other uses the command line.
Connect through pgAdmin III to the PostgreSQL Database
- In Windows, navigate to through the Start to the pgAdmin III menu option.
- After launching pgAdmin III, you’ll see the pgAdmin II console, displayed at left.
- Right click on the PostgreSQL 9.3 (localhost:5432) item in the Object browser and click the Connect menu choice from the floating menu.
- Enter the password you chose when installing the PostgreSQL Server, and click the OK button.
Connect through the Command-line to the PostgreSQL Database
These steps show you how to connect through the PostgreSQL Command Line Interface (CLI) – psql. psql is like Oracle’s sqlplus, MySQL’s mysql, and Microsoft SQL Server’s sqlcmd CLI interfaces. By default, the PostgreSQL binary directory is not in your default %PATH% environment variable, so you need to add it. I recommend an environment file because in a test situation you may not want to use it all the time.
Create the following directory for the environment file:
C:\Data\PostgreSQL\env |
You can create an environment file with any text editor or do it at the command line, like this:
COPY CON postgresqlenv.bat SET PATH=%PATH%;C:\Program Files\PostgreSQL\9.3\bin;. ^Z |
Then, you can source the environment file like this:
C:\> postgresql.bat |
Now, you can connect to the default database provided you understand that PostgreSQL Stack Builder set some values that differ from the defaults if you installed it manually. Specifically, they set the default value of the database to postgres and default value of the user to postgres.
That means you can connect with the following, provided you remember the password you used during installation:
C:\> psql -d postgres -U postgres |
You should see the following when you connect:
C:\> psql -d postgres -U postgres Password for user postgres: psql (9.3.3) WARNING: Console code page (437) differs from Windows code page (1252) 8-bit characters might not work correctly. See psql reference page "Notes for Windows users" for details. Type "help" for help. |
You can now submit interactive SQL statements or run batch files, like:
postgres=# SELECT 'Hello World!'; |
It displays:
?COLUMN? -------------- Hello World! (1 ROW) |
Adding a column alias to the string literal gives a more readable formatted output:
postgres=# SELECT 'Hello World!' AS "String Literal"; |
It displays:
String Literal ---------------- Hello World! (1 ROW) |
PostgreSQL’s CLI Help
You have the ability to do a lot with the PostgreSQL psql CLI. The general command to discover help is help, and it displays the following:
postgres=# help You are USING psql, the command-line interface TO PostgreSQL. TYPE: \copyright FOR distribution terms \h FOR help WITH SQL commands \? FOR help WITH psql commands \g OR terminate WITH semicolon TO EXECUTE query \q TO quit |
You quit PostgreSQL with a \q command:
postgres=# \q |
You can find more help with the \HELP or the \? commands:
\HELP |
It displays the following:
Available help: ABORT CLUSTER DEALLOCATE END ALTER AGGREGATE COMMENT DECLARE EXECUTE ALTER COLLATION COMMIT DELETE EXPLAIN ALTER CONVERSION COMMIT PREPARED DISCARD FETCH ALTER DATABASE COPY DO GRANT ALTER DEFAULT PRIVILEGES CREATE AGGREGATE DROP AGGREGATE INSERT ALTER DOMAIN CREATE CAST DROP CAST LISTEN ALTER EVENT TRIGGER CREATE COLLATION DROP COLLATION LOAD ALTER EXTENSION CREATE CONVERSION DROP CONVERSION LOCK ALTER FOREIGN DATA WRAPPER CREATE DATABASE DROP DATABASE MOVE ALTER FOREIGN TABLE CREATE DOMAIN DROP DOMAIN NOTIFY ALTER FUNCTION CREATE EVENT TRIGGER DROP EVENT TRIGGER PREPARE ALTER GROUP CREATE EXTENSION DROP EXTENSION PREPARE TRANSACTION ALTER INDEX CREATE FOREIGN DATA WRAPPER DROP FOREIGN DATA WRAPPER REASSIGN OWNED ALTER LANGUAGE CREATE FOREIGN TABLE DROP FOREIGN TABLE REFRESH MATERIALIZED VIEW ALTER LARGE OBJECT CREATE FUNCTION DROP FUNCTION REINDEX ALTER MATERIALIZED VIEW CREATE GROUP DROP GROUP RELEASE SAVEPOINT ALTER OPERATOR CREATE INDEX DROP INDEX RESET ALTER OPERATOR CLASS CREATE LANGUAGE DROP LANGUAGE REVOKE ALTER OPERATOR FAMILY CREATE MATERIALIZED VIEW DROP MATERIALIZED VIEW ROLLBACK ALTER ROLE CREATE OPERATOR DROP OPERATOR ROLLBACK PREPARED ALTER RULE CREATE OPERATOR CLASS DROP OPERATOR CLASS ROLLBACK TO SAVEPOINT ALTER OPERATOR CREATE INDEX DROP INDEX RESET ALTER OPERATOR CLASS CREATE LANGUAGE DROP LANGUAGE REVOKE ALTER OPERATOR FAMILY CREATE MATERIALIZED VIEW DROP MATERIALIZED VIEW ROLLBACK ALTER ROLE CREATE OPERATOR DROP OPERATOR ROLLBACK PREPARED ALTER RULE CREATE OPERATOR CLASS DROP OPERATOR CLASS ROLLBACK TO SAVEPOINT ALTER SCHEMA CREATE OPERATOR FAMILY DROP OPERATOR FAMILY SAVEPOINT ALTER SEQUENCE CREATE ROLE DROP OWNED SECURITY LABEL ALTER SERVER CREATE RULE DROP ROLE SELECT ALTER TABLE CREATE SCHEMA DROP RULE SELECT INTO ALTER TABLESPACE CREATE SEQUENCE DROP SCHEMA SET ALTER TEXT SEARCH CONFIGURATION CREATE SERVER DROP SEQUENCE SET CONSTRAINTS ALTER TEXT SEARCH DICTIONARY CREATE TABLE DROP SERVER SET ROLE ALTER TEXT SEARCH PARSER CREATE TABLE AS DROP TABLE SET SESSION AUTHORIZATION ALTER TEXT SEARCH TEMPLATE CREATE TABLESPACE DROP TABLESPACE SET TRANSACTION ALTER TRIGGER CREATE TEXT SEARCH CONFIGURATION DROP TEXT SEARCH CONFIGURATION SHOW ALTER TYPE CREATE TEXT SEARCH DICTIONARY DROP TEXT SEARCH DICTIONARY START TRANSACTION ALTER USER CREATE TEXT SEARCH PARSER DROP TEXT SEARCH PARSER TABLE ALTER USER MAPPING CREATE TEXT SEARCH TEMPLATE DROP TEXT SEARCH TEMPLATE TRUNCATE ALTER VIEW CREATE TRIGGER DROP TRIGGER UNLISTEN ANALYZE CREATE TYPE DROP TYPE UPDATE BEGIN CREATE USER DROP USER VACUUM CHECKPOINT CREATE USER MAPPING DROP USER MAPPING VALUES CLOSE CREATE VIEW DROP VIEW WITH |
You can find more help with the \HELP or the \? commands:
\? |
It displays the following:
General
\copyright show PostgreSQL usage and distribution terms
\g [FILE] or ; execute query (and send results to file or |pipe)
\gset [PREFIX] execute query and store results in psql variables
\h [NAME] help on syntax of SQL commands, * for all commands
\q quit psql
\watch [SEC] execute query every SEC seconds
Query Buffer
\e [FILE] [LINE] edit the query buffer (or file) with external editor
\ef [FUNCNAME [LINE]] edit function definition with external editor
\p show the contents of the query buffer
\r reset (clear) the query buffer
\s [FILE] display history or save it to file
\w FILE write query buffer to file
Input/Output
\copy ... perform SQL COPY with data stream to the client host
\echo [STRING] write string to standard output
\i FILE execute commands from file
\ir FILE as \i, but relative to location of current script
\o [FILE] send all query results to file or |pipe
\qecho [STRING] write string to query output stream (see \o)
Informational
(options: S = show system objects, + = additional detail)
\d[S+] list tables, views, and sequences
\d[S+] NAME describe table, view, sequence, or index
\da[S] [PATTERN] list aggregates
\db[+] [PATTERN] list tablespaces
\dc[S+] [PATTERN] list conversions
\dC[+] [PATTERN] list casts
\dd[S] [PATTERN] show object descriptions not displayed elsewhere
\ddp [PATTERN] list default privileges
\dD[S+] [PATTERN] list domains
\det[+] [PATTERN] list foreign tables
\des[+] [PATTERN] list foreign servers
\deu[+] [PATTERN] list user mappings
\dew[+] [PATTERN] list foreign-data wrappers
\df[antw][S+] [PATRN] list [only agg/normal/trigger/window] functions
\dF[+] [PATTERN] list text search configurations
\dFd[+] [PATTERN] list text search dictionaries
\dFp[+] [PATTERN] list text search parsers
\dFt[+] [PATTERN] list text search templates
\dg[+] [PATTERN] list roles
\di[S+] [PATTERN] list indexes
\dl list large objects, same as \lo_list
\dL[S+] [PATTERN] list procedural languages
\dm[S+] [PATTERN] list materialized views
\dn[S+] [PATTERN] list schemas
\do[S] [PATTERN] list operators
\dO[S+] [PATTERN] list collations
\dp [PATTERN] list table, view, and sequence access privileges
\drds [PATRN1 [PATRN2]] list per-database role settings
\ds[S+] [PATTERN] list sequences
\dt[S+] [PATTERN] list tables
\dT[S+] [PATTERN] list data types
\du[+] [PATTERN] list roles
\dv[S+] [PATTERN] list views
\dE[S+] [PATTERN] list foreign tables
\dx[+] [PATTERN] list extensions
\dy [PATTERN] list event triggers
\l[+] [PATTERN] list databases
\sf[+] FUNCNAME show a function's definition
\z [PATTERN] same as \dp
Formatting
\a toggle between unaligned and aligned output mode
\C [STRING] set table title, or unset if none
\f [STRING] show or set field separator for unaligned query output
\H toggle HTML output mode (currently off)
\pset NAME [VALUE] set table output option
(NAME := {format|border|expanded|fieldsep|fieldsep_zero|footer|null|
numericlocale|recordsep|recordsep_zero|tuples_only|title|tableattr|pager})
\t [on|off] show only rows (currently off)
\T [STRING] set HTML <table> tag attributes, or unset if none
\x [on|off|auto] toggle expanded output (currently off)
Connection
\c[onnect] {[DBNAME|- USER|- HOST|- PORT|-] | conninfo}
connect to new database (currently "studentdb")
\encoding [ENCODING] show or set client encoding
\password [USERNAME] securely change the password for a user
\conninfo display information about current connection
Operating System
\cd [DIR] change the current working directory
\setenv NAME [VALUE] set or unset environment variable
\timing [on|off] toggle timing of commands (currently off)
\! [COMMAND] execute command in shell or start interactive shell
Variables
\prompt [TEXT] NAME prompt user to set internal variable
\set [NAME [VALUE]] set internal variable, or list all if no parameters
\unset NAME unset (delete) internal variable
Large Objects
\lo_export LOBOID FILE
\lo_import FILE [COMMENT]
\lo_list
\lo_unlink LOBOID large object operations |
Have fun exploring PostgreSQL. You can click here to learn how to setup your own tablespace, database, and user. As always, I hope this helps those looking to discover how to install and use PostgreSQL.
Subscribe via RSS