Shulou(Shulou.com)06/01 Report--

Single table query: SELECT [DISTINCT] [SQL_CACHE | SQL_NO_CACHE] select_expr [, select_expr...] [FROM table_references [WHERE where_condition] [GROUP BY {col_name | expr |}] [HAVING where_condition] [ORDER BY [ASC | DESC]] DISTINCT: data deduplication SQL_CACHE: specify cache SQL_NO_CACHE: specify cache WHERE clause: specify condition Filter condition: arithmetic operation: +-* /% >

= CREATE DATABASE mydb; # create test database mysql > USE mydb; mysql > CREATE TABLE test (id int (50), name varchar (50), qq int (15), gender char (2); # create test table mysql > INSERT INTO test VALUES Mysql > INSERT INTO test VALUES; mysql > SELECT * FROM test WHERE id > 2 AND id SELECT * FROM test WHERE id > 2 GROUP BY gender; # grouping by gender mysql > SELECT sum (id), gender FROM test GROUP BY gender # grouping gender and asking for the sum of their id mysql > SELECT * FROM test GROUP BY gender HAVING id > 2; # grouping gender to show that the group with id greater than 2 has a multi-table association query: mysql > CREATE TABLE test2 (emain varchar (200), age int (10)); # create a test environment mysql > INSERT INTO test2 values ('123 roomqq.composition10) Mysql > INSERT INTO test2 values ('456 roomqq.compositional Magna 15); mysql > INSERT INTO test2 values (' 789 roomqq.compositional Magnesia 20); mysql > SELECT test.id,test2.age FROM test,test2 WHERE test.id > 2 AND test2.age > 10 Test.id # Chapter I Table id Field test2.age # Chapter II Table age Field test # Chapter I Table name test2 # Chapter II Table name test.id > 2 AND test2.age # splice display test's id field and test2's age field But the id field of test must be greater than 2 and the age field of test2 must be greater than 10 mysql > SELECT * FROM test,test2 WHERE test.id > 2 AND test2.age > 10 # splicing shows all fields of test,test2, but the id field of test must be greater than 2 and the age field of test2 must be greater than 10

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