![]() Increase the precision of the specified number column.ĭecrease the precision of the specified number column if the new precision is sufficient to holdįor text data types, TYPE can be used only to increase the length of the column. type) must beįor the NUMBER data type, TYPE can be used to: When setting the TYPE for a column, the specified type (i.e. The default value for rows inserted after the column was added.ĭropping the default column value from any clone of the table is also prohibited. If the default were dropped, then the column would contain:Ī NULL value for rows inserted before the column was added. Rows inserted after the column was added. This restriction prevents inconsistency between values in rows inserted before the column was added and If you alter a table to add a column with a DEFAULT value, then you cannot drop the default value for that column.įor example, in the following sequence of statements, the last ALTER TABLE. SET DEFAULT to add a sequence to a column that does not already have a sequence. To change the default sequence for a column, the column must already have a default sequence. Setting these columns to NOT NULL when the table contains rows is not supported and results in an error. When setting a column to NOT NULL, if the column contains NULL values, an error is returned and no changes are applied to the column.Ĭolumns that use semi-structured data types (ARRAY, OBJECT, and VARIANT) cannot be set to NOT NULL, except when the table is empty. The clauses can be specified in any order. The COLUMN keyword can be specified in each clause, but is not required. Parentheses can be used for grouping the clauses, but are not required. columns/properties to modify) in the statement. Use either the ALTER or MODIFY keyword to initiate the list of clauses (i.e. ALTER TABLE COLUMN UNSET TAG, COLUMN UNSET TAG.
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