); When we run on  test2  the same two  REPLACE  statements as we did on the original  test  table, we obtain a different result: This is due to the fact that, when run on  test2 , both the  id  and  ts  column values must match those of an existing row for the row to be replaced; otherwise, a row is inserted. SELECT  is used to retrieve rows selected from one or more tables, and can include  UNION  statements and subqueries. See Section 13.2.10.3, “UNION Clause” , and Section 13.2.11, “Subqueries” . A  SELECT statement can start with a  WITH  clause to define common table expressions accessible within the  SELECT . See Section 13.2.15, “WITH (Common Table Expressions)” . The most commonly used clauses of  SELECT  statements are these: 2661 SELECT [ALL | DISTINCT | DISTINCTROW ] [HIGH_PRIORITY] [STRAIGHT_JOIN] [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] [SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] select_expr  [,  select_expr ] ... [ into_option ] [FROM  table_references [PARTITION  partition_list ]] [WHERE  where_condition ] [GROUP BY { col_name  |  expr  |  position }, ... [WITH ROLLUP]] [HAVING  where_condition ] [WINDOW  window_name  AS ( window_spec ) [,  window_name  AS ( window_spec )] ...] [ORDER BY { col_name  |  expr  |  position } [ASC | DESC], ... [WITH ROLLUP]] [LIMIT {[ offset ,]  row_count  |  row_count  OFFSET  offset }] [ into_option ] [FOR {UPDATE | SHARE} [OF  tbl_name  [,  tbl_name ] ...] [NOWAIT | SKIP LOCKED] | LOCK IN SHARE MODE] [ into_option ] into_option : { INTO OUTFILE ’ file_name ’ [CHARACTER SET  charset_name ] export_options | INTO DUMPFILE ’ file_name ’ | INTO  var_name  [,  var_name ] ... } mysql>  REPLACE INTO test2 VALUES (1, ’Old’, ’2014-08-20 18:47:00’); Query OK, 1 row affected (0.05 sec) mysql>  REPLACE INTO test2 VALUES (1, ’New’, ’2014-08-20 18:47:42’); Query OK, 1 row affected (0.06 sec) mysql>  SELECT * FROM test2; +----+------+---------------------+ | id | data | ts | +----+------+---------------------+ | 1 | Old | 2014-08-20 18:47:00 | | 1 | New | 2014-08-20 18:47:42 | +----+------+---------------------+ 2 rows in set (0.00 sec) 13.2.10 SELECT Statement SELECT Statement