1. 查询操作(SELECT)

简单查询SELECT * FROM table_name;

条件查询SELECT column_name FROM table_name WHERE condition;

分组查询SELECT column_name, sum(column_value) FROM table_name GROUP BY column_name;

子查询SELECT column_name FROM subquery AS source WHERE condition;

连接查询SELECT column_name1, column_name2 FROM table1 JOIN table2 ON condition;

内联子查询SELECT column_name FROM table1 WHERE condition AND SELECT column_name FROM table2 WHERE condition;

多表连接查询SELECT column_name1, column_name2 FROM table1 JOIN table2 ON condition AND SELECT column_name3 FROM table3 JOIN table4 ON condition;

UNION ALL查询SELECT column_name1, column_name2 FROM table1 UNION SELECT column_name3, column_name4 FROM table2;

UNION查询SELECT column_name1, column_name2 FROM table1 UNION SELECT column_name3, column_name4 FROM table2 UNION SELECT column_name5, column_name6 FROM table3;

MINUS查询SELECT column_name1, column_name2 FROM table1 MINUS SELECT column_name3, column_name4 FROM table2;

MAXIMUM查询SELECT column_name1, column_name2 FROM table1 MAXIMUM SELECT column_name3, column_name4 FROM table2;

AVG查询SELECT AVG(column_value) FROM table1;

COUNT查询SELECT COUNT(*) FROM table1;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition AND SELECT COUNT(*) FROM table5 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition AND SELECT COUNT(*) FROM table5 WHERE condition AND SELECT COUNT(*) FROM table6 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition AND SELECT COUNT(*) FROM table5 WHERE condition AND SELECT COUNT(*) FROM table6 WHERE condition AND SELECT COUNT(*) FROM table7 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition AND SELECT COUNT(*) FROM table5 WHERE condition AND SELECT COUNT(*) FROM table6 WHERE condition AND SELECT COUNT(*) FROM table7 WHERE condition AND SELECT COUNT(*) FROM table8 WHERE condition;

COUNT(*)查询SELECT COUNT(*) FROM table1 WHERE condition AND SELECT COUNT(*) FROM table2 WHERE condition AND SELECT COUNT(*) FROM table3 WHERE condition AND SELECT COUNT(*) FROM table4 WHERE condition AND SELECT COUNT(*) FROM table5 WHERE condition AND SELECTCOUNT()FROMtable6WHEREconditionANDSELECTCOUNT()FROMtable7WHEREconditionANDSELECTCOUNT()FROMtable8WHEREcondition;

NULL值处理IFNULL(column_value, ”);

ISNULL函数ISNULL(column_value);

COALESCE函数COALESCE(column_value1, column_value2);

IF函数IF(condition, value1, value2);