Mysql updating multiple tables

Posted by / 14-Dec-2017 03:26

(Because the procedure for installing My SQL is different on each platform, and because the installation process is nearly automatic in modern times, I've decided not to cover installation issues.

At this point I assume the reader has successfully installed My SQL and has logon authority in the system.) Start the My SQL command-line application I'll make this one concession to the differences between platforms: NOTE: There's an alternative to telling My SQL which database to use — one simply prepends the database name to each table reference, like this: "database_name.table_name".

For information about the physical representation of a table, see Section, “Files Created by CREATE TABLE”.

The original statement, including all specifications and table options are stored by My SQL when the table is created.

UPDATE table SET Col1 = 1 WHERE id = 1; UPDATE table SET Col1 = 2 WHERE id = 2; UPDATE table SET Col2 = 3 WHERE id = 3; UPDATE table SET Col1 = 10 WHERE id = 4; UPDATE table SET Col2 = 12 WHERE id = 4; If there is no duplicates then i dont want that row to be inserted. because i am fetching information from another site which maintains tables with id's. if the site has new records then i will end up inserting only the ids and count except all other information.

if and only if there is an entry for the id then it should update else it should skip. $operation Checked) $command Txt .= " WHEN $operation ID THEN $operation Checked "; $command Txt .= ' ELSE id END WHERE id IN ('.implode(', ', array_keys(block Operation Checked )).');'; variant, a variant with "case / when / then" clause and a naive approach with transaction. The overall conclusion is that the variant with case statement turns out to be twice as fast as two other variants, but it's quite hard to write correct and injection-safe code for it, so I personally stick to the simplest approach: using transactions.

For more information, see Section, “CREATE TABLE Statement Retention”.

The TRANSACTION method is also pretty expensive in both replication and query logs.

These options apply to all storage engines unless otherwise indicated.

Options that do not apply to a given storage engine may be accepted and remembered as part of the table definition.

So in general, I feel the INSERT method is both best and easiest to use.

The queries are smaller and easier to read and only take up 1 query of action. Bonus stuff: The solution for the INSERT non-default-field problem is to temporarily turn off the relevant SQL modes: first if you plan on reverting it. SQL files to remove php interpreter overhead There is a setting you can alter called 'multi statement' that disables My SQL's 'safety mechanism' implemented to prevent (more than one) injection command.

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