UPDATE component_name
SET col_name1=expr1 [, col_name2=expr2 ...]
[WHERE where_condition]
[ORDER BY ...]
[LIMIT record_count]
The UPDATE statement updates columns of existing records in component_name with new values and returns the number of affected records.
The SET clause indicates which columns to modify and the values they should be given.
The optional WHERE clause specifies the conditions that identify which records to update.
Without WHERE clause, all records are updated.
The optional ORDER BY clause specifies the order in which the records are being updated.
The LIMIT clause places a limit on the number of records that can be updated. You can use LIMIT row_count to restrict the scope of the UPDATE.
A LIMIT clause is a rows-matched restriction not a rows-changed restriction.
The statement stops as soon as it has found record_count rows that satisfy the WHERE clause, whether or not they actually were changed.