SQL DELETE
Mit DELETE werden einzelne oder mehrere Datensätze gelöscht. Mit WHERE
werden nur bestimmte Datensätez gelöscht.
DELETE FROM suppliers
WHERE
supplier_name = 'Microsoft';
SQL DELETE
Mit DELETE werden einzelne oder mehrere Datensätze gelöscht. Mit WHERE
werden nur bestimmte Datensätez gelöscht.
DELETE FROM suppliers
WHERE
supplier_name = 'Microsoft';
sql delete
DELETE FROM my_table; -- all rows
DELETE FROM my_table WHERE my_id = 12345;
DELETE FROM my_table WHERE my_id IN (SELECT id2 FROM my_table2);
COMMIT; -- don't forget it...
sql delete
Delete data from a table.
Example: Removes a user with a user_id of 674.
DELETE FROM users WHERE user_id = 674;
what is delete in sql
DELETE -
-DML COMMAND
-Delete Rows from the table one by one
-We can use where clause with Delete to delete single row
-Delete is slower than truncate
-ROLLBACK is possible with DELETE
DROP-
-DDL COMMAND
-Delete the entire structure or schema
-We can't use where clause with drop
-Drop is slower than DELETE & TRUNCATE
-ROLLBACK IS NOT POSSIBLE WITH DROP
TRUNCATE-
-DDL COMMAND
-Truncate deletes rows at a one goal
-We can't use where clause with Truncate
-Truncate faster than both DELETE & DROP
-Rollback is not possible with Truncate
mysql on delete set null
FOREIGN KEY (child_col1, child_col2, ... child_col_n)
REFERENCES parent_table (parent_col1, parent_col2, ... parent_col_n)
ON DELETE SET NULL
[ ON UPDATE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ]
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