Data Changes (DML)

Data Manipulation Language: statements that change rows in a table without changing the table's shape. Insert, update, delete, truncate, ups...

Add new rows to a table: from literal values, from another query, or from a one-off file load. Two flavors cover most real work: INSERT ... ...

Change values in existing rows. The SET clause says what to change; the WHERE clause says which rows. Forgetting the WHERE clause updates th...

Remove rows from a table. The table itself stays, the indexes stay, the constraints stay. Only the matched rows leave. DELETE FROM t with no...

Empty a table fast. Conceptually DELETE FROM t with no WHERE, but implemented very differently: most engines deallocate the underlying pages...

Insert-or-update in one statement. The engine matches incoming rows against an existing target on a key; matches get updated, non-matches ge...