SQL 语法总结

学了一个月的java，开始有入门的感觉。这段时间接触到了java的JDBC, 发现学习这部分的内容还是要有SQL的基础，于是花费了几天时间学习了一下SQL语法，并将其总结于下。

选择数据 SELECT * FROM table;

排序数据 SELECT [a,b,c] FROM table ORDER BY [a,b]; //先按照a列排序，相同的再按照b列排序

过滤数据 SELECT [a,b] FROM table WHERE condition;

高级过滤 SELECT [a,b] FROM table WHERE condition1 AND/OR condition2;

通配符过滤 SELECT [a,b] FROM table WHERE a LIKE 'fish%'; // [%],[_],[[]]三个通配符

计算字段 SELECT a + '('+b+')' FROM table ORDER BY a; //拼接

SELECT RTRIM(a)+'('RTRIM(b)')' AS c FROM table ORDER BY a; //列别名

函数字段 SELECT [a,b] FROM table WHERE SOUNDEX(a) = SOUNDEX('tim'); //根据发音匹配

汇总数据 SELECT AVG(a) AS c FROM table WHERE condition; // COUNT(), MAX(), MIN(), SUM()汇总函数

分组数据 SELECT a, COUNT() AS c FROM table GROUP BY a; // 创建分组

SELECT a, COUNT() AS c FROM table GROUP BY a HAVING condition; // 过滤分组

SELECT - FROM - WHERE - GROUP BY - HAVING - ORDER BY // 分组语句的关键词顺序

组合查询 SELECT [a,b] FROM table WHERE c IN('MI') UNION SELECT [a,b] FROM table WHERE condition;

插入数据 INSERT INTO table VALUES('','',''...);

INSERT INTO table2(a,b,c) SELECT a,b,c FROM table1; // 插入检索的数据

SELECT * INTO table2 FROM table1; // 复制表

更新数据 UPDATE table SET a='' WHERE condition;

删除数据 DELETE FROM table WHERE condition;

创建表 CREATE TABLE table {...};

更新表 ALTER TABLE table ADD a CHAR(20);

删除表 DROP TABLE table;

注： 本内容总结自《SQL必知必会》

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