Oracle Diagnostic Queries
It’s always a challenge when you want to build your own Oracle SQL Tools. I was asked how you could synchronize multiple cursors into a single source. The answer is quite simple, you write an Oracle object type to represent a record structure, an Oracle list of the record structure, and a stored function to return the list of the record structure.
For this example, you create the following table_struct object type and a table_list collection type:
/* Drop the types from most to least dependent. */ DROP TYPE table_list; DROP TYPE table_struct; /* Create the record type structure. */ CREATE OR REPLACE TYPE table_struct IS OBJECT ( table_name VARCHAR2(30) , column_cnt NUMBER , row_cnt NUMBER ); / /* Create the collection of a record type structure. */ CREATE OR REPLACE TYPE table_list IS TABLE OF table_struct; / |
The following listing function now reads all table names from the user_tables view. A subordinate cursor reads the user_tab_columns view for the number of columns in a table. A Native Dynamic SQL (NDS) cursor counts the number of rows in each tables found in the .
/* Create the listing function. */
CREATE OR REPLACE
FUNCTION listing RETURN table_list IS
/* Variable list. */
lv_column_cnt NUMBER;
lv_row_cnt NUMBER;
/* Declare a statement variable. */
stmt VARCHAR2(200);
/* Declare a system reference cursor variable. */
lv_refcursor SYS_REFCURSOR;
lv_table_cnt NUMBER;
/* Declare an output variable. */
lv_list TABLE_LIST := table_list();
/* Declare a table list cursor that excludes APEX tables. */
CURSOR c IS
SELECT table_name
FROM user_tables
WHERE table_name NOT IN
('DEPT','EMP','APEX$_ACL','APEX$_WS_WEBPG_SECTIONS','APEX$_WS_ROWS'
,'APEX$_WS_HISTORY','APEX$_WS_NOTES','APEX$_WS_LINKS'
,'APEX$_WS_TAGS','APEX$_WS_FILES','APEX$_WS_WEBPG_SECTION_HISTORY'
,'DEMO_USERS','DEMO_CUSTOMERS','DEMO_ORDERS','DEMO_PRODUCT_INFO'
,'DEMO_ORDER_ITEMS','DEMO_STATES');
/* Declare a column count. */
CURSOR cnt
( cv_table_name VARCHAR2 ) IS
SELECT table_name
, COUNT(column_id) AS cnt_columns
FROM user_tab_columns
WHERE table_name = cv_table_name
GROUP BY table_name;
BEGIN
/* Read through the data set of non-environment variables. */
FOR i IN c LOOP
/* Count the columns of a table. */
FOR j IN cnt(i.table_name) LOOP
lv_column_cnt := j.cnt_columns;
END LOOP;
/* Declare a statement. */
stmt := 'SELECT COUNT(*) AS column_cnt FROM '||i.table_name;
/* Open the cursor and write set to collection. */
OPEN lv_refcursor FOR stmt;
LOOP
FETCH lv_refcursor INTO lv_table_cnt;
EXIT WHEN lv_refcursor%NOTFOUND;
lv_list.EXTEND;
lv_list(lv_list.COUNT) := table_struct(
table_name => i.table_name
, column_cnt => lv_column_cnt
, row_cnt => lv_table_cnt );
END LOOP;
END LOOP;
RETURN lv_list;
END;
/ |
The following query pulls the processed data set as the function’s result:
COL table_name FORMAT A20 HEADING "Table Name" COL column_cnt FORMAT 9,999 HEADING "Column #" COL row_cnt FORMAT 9,999 HEADING "Row #" SELECT table_name , column_cnt , row_cnt FROM TABLE(listing); |
It returns the following result set:
Table Name Column # Row # -------------------- -------- ------ SYSTEM_USER 11 5 COMMON_LOOKUP 10 49 MEMBER 9 10 CONTACT 10 18 ADDRESS 10 18 STREET_ADDRESS 8 28 TELEPHONE 11 18 RENTAL 8 4,694 ITEM 14 93 RENTAL_ITEM 9 4,703 PRICE 11 558 TRANSACTION 12 4,694 CALENDAR 9 300 AIRPORT 9 6 ACCOUNT_LIST 8 200 15 rows selected. |
As always, I hope this helps those trying to work with the Oracle database.
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