Archive for the ‘Oracle Development’ tag
Leaf node queries
A reader posted A dynamic level limiting hierarchical query about Oracle’s hierarchical queries. They wanted to know how to capture only the hierarchy above the level where the first leaf node occurs. They gave me the following hierarchy map as an example:
1 2
+-------------+ +-----------+
| | | |
3 5 4 6
+---------+ +-----------+ +-----+ +------+
| | | | | | | |
7 9 11 13 8 10 12 14
+-----+ +-----+ +--+ +-------+ +-----+
| | | | | | | | |
15 17 19 21 23 27 29 16 18
+---+
|
20 |
You can find the node values and hierarchical level with the following query:
SELECT tt.child_id , LEVEL FROM test_temp tt WHERE CONNECT_BY_ISLEAF = 1 START WITH tt.parent_id IS NULL CONNECT BY PRIOR tt.child_id = tt.parent_id ORDER BY 2; |
We really don’t need the node values to solve the problem. We only need the lowest LEVEL value returned by the query, which is 3. The combination of the MIN and CONNECT_BY_ISLEAF functions let us solve this problem without writing a PL/SQL solution. The subquery returns the lowest level value, which is the first level where a leaf node occurs.
SELECT LPAD(' ', 2*(LEVEL - 1)) || tt.child_id AS child_id FROM test_temp tt WHERE LEVEL <= (SELECT MIN(LEVEL) FROM test_temp tt WHERE CONNECT_BY_ISLEAF = 1 START WITH tt.parent_id IS NULL CONNECT BY PRIOR tt.child_id = tt.parent_id) START WITH tt.parent_id IS NULL CONNECT BY PRIOR tt.child_id = tt.parent_id; |
It returns:
1 2
+-------------+ +-----------+
| | | |
3 5 4 6
+---------+ +-----------+ +-----+ +------+
| | | | | | | |
7 9 11 13 8 10 12 14 |
While I answered the question in a comment originally, it seemed an important trick that should be shared in its own post.
Wrapping SQL*Plus
One annoying thing from installing Oracle Database 11g on Fedora, was that the up arrows for command history didn’t work. I decided to fix that today after seeing Lutz Hartmann’s article on rlwrap. Unfortunately, the epel (Extra Packages for Enterprise Linux) package he recommended doesn’t run on Fedora 20. You can read my tale of woe, or skip to the .bashrc function that fixed it when I installed only rlwrap.
Attempting it on yum, gave me these errors:
# yum install http://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm Loaded plugins: langpacks, refresh-packagekit epel-release-6-8.noarch.rpm | 14 kB 00:00 Examining /var/tmp/yum-root-5CLTPa/epel-release-6-8.noarch.rpm: epel-release-6-8.noarch Marking /var/tmp/yum-root-5CLTPa/epel-release-6-8.noarch.rpm to be installed Resolving Dependencies --> Running transaction check ---> Package epel-release.noarch 0:6-8 will be installed --> Processing Conflict: epel-release-6-8.noarch conflicts fedora-release No package matched to upgrade: epel-release --> Finished Dependency Resolution Error: epel-release conflicts with fedora-release-20-3.noarch You could try using --skip-broken to work around the problem You could try running: rpm -Va --nofiles –nodigest |
Poking around for an epel fix wasn’t successful, so I chose to install only the rlwrap package. Here’s that command and log file:
[root@localhost ~]# yum install rlwrap Loaded plugins: langpacks, protectbase, refresh-packagekit 0 packages excluded due to repository protections Resolving Dependencies --> Running transaction check ---> Package rlwrap.x86_64 0:0.41-1.fc20 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: rlwrap x86_64 0.41-1.fc20 updates 95 k Transaction Summary ================================================================================ Install 1 Package Total download size: 95 k Installed size: 204 k Is this ok [y/d/N]: y Downloading packages: rlwrap-0.41-1.fc20.x86_64.rpm | 95 kB 00:00 Running transaction check Running transaction test Transaction test succeeded Running transaction (shutdown inhibited) Installing : rlwrap-0.41-1.fc20.x86_64 1/1 Verifying : rlwrap-0.41-1.fc20.x86_64 1/1 Installed: rlwrap.x86_64 0:0.41-1.fc20 Complete! |
The next step was getting it to work. A sqlplus function wrapper inside the .bashrc file seemed the easiest. Here’s the code to the .bashrc file:
# .bashrc # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi # Uncomment the following line if you don't like systemctl's auto-paging feature: # export SYSTEMD_PAGER= # User specific aliases and functions . /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh # Wrap sqlplus with rlwrap to edit prior lines. sqlplus() { if [ "$RLWRAP" = "0" ]; then sqlplus "$@" else rlwrap sqlplus "$@" fi } # Set vi as a command line editor. set -o vi |
As always, I hope this helps some folks.
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