COLUMN_ADD

MariaDB starting with 5.3

The Dynamic columns feature was introduced in MariaDB 5.3.

Syntax

COLUMN_ADD(dyncol_blob, column_nr, value [as type], [column_nr, value [as type]]...);
COLUMN_ADD(dyncol_blob, column_name, value [as type], [column_name, value [as type]]...);

Description

Adds or updates dynamic columns.

  • dyncol_blob must be either a valid dynamic columns blob (for example, COLUMN_CREATE returns such blob), or an empty string.
  • column_name specifies the name of the column to be added. If dyncol_blob already has a column with this name, it will be overwritten.
  • value specifies the new value for the column. Passing a NULL value will cause the column to be deleted.
  • as type is optional. See #datatypes section for a discussion about types.

The return value is a dynamic column blob after the modifications.

Examples

-- MariaDB 5.3+:
UPDATE tbl SET dyncol_blob=COLUMN_ADD(dyncol_blob, 1 /*column id*/, "value") WHERE id=1;
-- MariaDB 10.0.1+:
UPDATE t1 SET dyncol_blob=COLUMN_ADD(dyncol_blob, "column_name", "value") WHERE id=1;

Note: COLUMN_ADD() is a regular function (just like CONCAT()), hence, in order to update the value in the table you have to use the UPDATE ... SET dynamic_col=COLUMN_ADD(dynamic_col, ....) pattern.

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