When to use on duplicate key update in MariaDB?
This function is particularly useful for multi-rows inserts. The IGNORE and DELAYED options are ignored when you use ON DUPLICATE KEY UPDATE. The PARTITION clause was introduced in MariaDB 10.0. See Partition Pruning and Selection for details. This statement activates INSERT and UPDATE triggers.
When do you need to version a table in MariaDB?
Another MariaDB extension allows to version only a subset of columns in a table. This is useful, for example, if you have a table with user information that should be versioned, but one column is, let’s say, a login counter that is incremented often and is not interesting to version.
Is it safe to add two unique columns in MariaDB?
Note that there are two rows reported as affected, but this refers only to the UPDATE. Adding a second unique column: Where two rows match the unique keys match, only the first is updated. This can be unsafe and is not recommended unless you are certain what you are doing.
Which is the temporal data table in MariaDB?
MariaDB supports temporal data tables in the form of system-versioning tables (allowing you to query and operate on historic data, discussed below), application-time periods (allow you to query and operate on a temporal range of data), and bitemporal tables (which combine both system-versioning and application-time periods ).
What does insert on duplicate key update do?
INSERT ON DUPLICATE KEY UPDATE is a MariaDB/MySQL extension to the INSERT statement that, if it finds a duplicate unique or primary key, will instead perform an UPDATE. The row/s affected value is reported as 1 if a row is inserted, and 2 if a row is updated, unless the API’s CLIENT_FOUND_ROWS flag is set.
When to insert an empty value in MariaDB?
In all other cases, if a NOT NULL column without a DEFAULT value is not referenced, an empty value will be inserted (for example, 0 for INTEGER columns and ” for CHAR columns). See NULL Values in MariaDB:Inserting for examples. If a NOT NULL column having a DEFAULT value is not referenced, NULL will be inserted.