CREATE TABLE first ( a INTEGER, PRIMARY KEY (a) ) ; and CREATE TABLE second ( b INTEGER, aref INTEGER, PRIMARY KEY (b), KEY (aref) ); ALTER TABLE second ADD CONSTRAINT myforeignkey FOREIGN KEY (aref) REFERENCES first(a); Is there any restriction derived from the ...
| CHECK [ NOT FOR REPLICATION ] ( logical_expression ) } table_constraint[ CONSTRAINT constraint_name ] { [ { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] { ( column [ ,...n ] ) } [ WITH FILLFACTOR = fillfactor ] [ ON { filegroup | DEFAULT } ] ] | FOREIGN KEY [...
The ALTER TABLE command is used to change the structure of an existing table. It helps to add or delete columns, create or destroy indexes, change the type of existing columns, rename columns or the table itself. It can also be used to change the comment for the table and type of the ...
When you use the ALTER TABLE command to add or drop a unique or foreign-key constraint in a hybrid table, the corresponding index will also be created or dropped. For more information on indexes in a hybrid table, see CREATE INDEX. Foreign-key constraints are supported only across hybrid t...
Example 6. How to drop foreign key Constraint using Alter command: Suppose there is a foreign key constraint named'fk_roll_num'for the columnroll_number'of the'Marks'table and we want to drop this constraint ALTERTABLEMarksDROPCONSTRAINT'fk_roll_num’; ...
You can also use the COLLATE clause in the ALTER TABLE command when appropriate (primary key or foreign key). FieldType [(nFieldWidth [, nPrecision])] Specifies the field type, field width, and field precision (number of decimal places) for the new or modified field. FieldType is a ...
Converting a column from sparse to nonsparse or from nonsparse to sparse locks the table for the duration of the command execution. You may need to use the REBUILD clause to reclaim any space savings. Important You must specify the SPARSE property each time you alter the column, or the ...
(thd) to the original CREATE TABLE command so InnoDB can pick the FK definitions from it. This bug could be related toBug#35521Foreign keys: ALTER is destructive a third solution is for MySQL to explicitly create the FKs on the temporary table after it creates it. If this is howBug#3...
PS:REORG TABLE本身是DB2的command,不是正常的SQL语句(Statement)。如果在非命令行环境中想使用REORG的话,可以像下面那样调用存储过程间接执行REORG操作,执行前确保你所使用的帐号有调用这个存储过程的权限: CALL SYSPROC.ADMIN_CMD('reorg table my_test') ...
3550 Peter Steiner December 03, 2010 03:07AM Re: Which restriction has adding a foreign key constraint in ALTER TABLE command? 1445 Boris Masnec December 08, 2010 01:15PM Sorry, you can't reply to this topic. It has been closed.