Updating a select


31-Oct-2017 13:00

Because of this indeterminacy, referencing other tables only within sub-selects is safer, though often harder to read and slower than using a join. [1] Set the value of column C1 in table T to 1, only in those rows where the value of column C2 is "a".PDF (US Ltr) - 26.9Mb PDF (A4) - 27.0Mb PDF (RPM) - 25.6Mb HTML Download (TGZ) - 6.5Mb HTML Download (Zip) - 6.5Mb HTML Download (RPM) - 5.6Mb Man Pages (TGZ) - 158.5Kb Man Pages (Zip) - 261.7Kb Info (Gzip) - 2.6Mb Info (Zip) - 2.6Mb My SQL Backup and Recovery My SQL NDB Cluster 7.2 My SQL Globalization My SQL Information Schema My SQL Installation Guide My SQL and Linux/Unix My SQL and OS X My SQL Partitioning My SQL Performance Schema My SQL Replication My SQL Restrictions and Limitations Security in My SQL My SQL and Solaris Building My SQL from Source Starting and Stopping My SQL My SQL Tutorial My SQL and Windows clause, are flagged as unsafe for statement-based replication.

If it does, then only one of the join rows will be used to update the target row, but which one will be used is not readily predictable.

So, I do it in one "magick" query ;)Here an example:"3" is a some value, from form or somethingupdate item set rate = case when round((rate 3)/2) You sometimes run into the problem that you want to replace a substring occuring in a column with a different string, without touching the rest of the string.

The solution is surprisingly simple, thanks to My SQL: UPDATE xoops_bb_posts_text SET post_text=( REPLACE (post_text, 'morphix.sourceforge.net', ' the string function REPLACE, all items in the post_text column with 'morphix.sourceforge.net' get this substring replaced by '

If you wish to use an increment based on subset of a table you may combine UPDATE with Variables:e.g.

A table that contains entries of different categories, in which an internal order needs to represented ( lets say a table with busstops on different routes).

If you add new entries or move stops from one route to another you will most likely want to increment the position of the busstop within this route.