mysql的四大分类用的最多的是DQL和DML吗？ dml是什么？
\u4ec0\u4e48\u662fDQL\uff0cDML\uff0cDDL\uff0cDCL\u5728\u4e00\u4e9b\u516c\u53f8\u4e2d\u63d0\u4ea4\u7ed9\u6d4b\u8bd5\u56e2\u961f\u7684SQL\u811a\u672c\u4f1a\u5212\u5206\u4e3aDDL\u3001DML\u7b49\uff0c\u4f46\u8fd9\u4e9b\u6982\u5ff5\u5230\u5e95\u662f\u5982\u4f55\u5b9a\u4e49\u7684\u5462\uff1f
SQL(Structure Query Language)\u662f\u6570\u636e\u5e93\u64cd\u4f5c\u7684\u7684\u6838\u5fc3\u8bed\u8a00\uff0c\u63a5\u4e0b\u6765\u6211\u4eec\u901a\u8fc7\u4e00\u5f20\u56fe\u6765\u8fdb\u884c\u5206\u6790\uff1a
\u5982\u679c\u5bf9\u7f16\u7a0b\u611f\u5174\u8da3\u53ef\u4ee5\u6765\u6211\u8fd9\u770b\u770b
DDL\uff08Data Definition Languages\uff09\u8bed\u53e5\uff1a \u5373\u6570\u636e\u5e93\u5b9a\u4e49\u8bed\u53e5\uff0c\u7528\u6765\u521b\u5efa\u6570\u636e\u5e93\u4e2d\u7684\u8868\u3001\u7d22\u5f15\u3001\u89c6\u56fe\u3001\u5b58\u50a8\u8fc7\u7a0b\u3001\u89e6\u53d1\u5668\u7b49\u5e38\u7528\u7684\u8bed\u53e5\u5173\u952e\u5b57\u6709\uff1aCREATE,ALTER,DROP,TRUNCATE,COMMENT,RENAME\u3002
DML\uff08Data Manipulation Language\uff09\u8bed\u53e5\uff1a \u5373\u6570\u636e\u64cd\u7eb5\u8bed\u53e5\uff0c\u7528\u6765\u67e5\u8be2\u3001\u6dfb\u52a0\u3001\u66f4\u65b0\u3001\u5220\u9664\u7b49\u5e38\u7528\u7684\u8bed\u53e5\u5173\u952e\u5b57\u6709\uff1aSELECT,INSERT,UPDATE,DELETE,MERGE,CALL,EXPLAIN PLAN,LOCK TABLE,\u5305\u62ec\u901a\u7528\u6027\u7684\u589e\u5220\u6539\u67e5\u3002
DCL\uff08Data Control Language\uff09\u8bed\u53e5\uff1a \u5373\u6570\u636e\u63a7\u5236\u8bed\u53e5\uff0c\u7528\u4e8e\u6388\u6743/\u64a4\u9500\u6570\u636e\u5e93\u53ca\u5176\u5b57\u6bb5\u7684\u6743\u9650\uff08DCL is short name of Data Control Language which includes commands such as GRANT and mostly concerned with rights, permissions and other controls of the database system.\uff09\u3002\u5e38\u7528\u7684\u8bed\u53e5\u5173\u952e\u5b57\u6709\uff1aGRANT,REVOKE\u3002
TCL\uff08Transaction Control Language\uff09\u8bed\u53e5\uff1a \u4e8b\u52a1\u63a7\u5236\u8bed\u53e5\uff0c\u7528\u4e8e\u63a7\u5236\u4e8b\u52a1\u5e38\u7528\u7684\u8bed\u53e5\u5173\u952e\u5b57\u6709\uff1aCOMMIT,ROLLBACK,SAVEPOINT,SET TRANSACTION\u3002
DQL:\uff08Data QueryLanguage\uff09\u8bed\u53e5\uff1a \u6570\u636e\u67e5\u8be2\u8bed\u8a00\u5e38\u7528\u7684\u8bed\u53e5\u5173\u952e\u5b57\u6709\uff1aSELECT, FROM, WHERE, ORDER BY, HAVING,ASC|DESC
\u5e0c\u671b\u5bf9\u60a8\u6709\u6240\u5e2e\u52a9\uff01~
DML\u662fData Manipulation Language\u7684\u7f29\u5199\uff0c\u610f\u601d\u662f\u6570\u636e\u64cd\u7eb5\u8bed\u8a00\uff0c\u662f\u6307\u5728SQL\u8bed\u8a00\u4e2d\uff0c\u8d1f\u8d23\u5bf9\u6570\u636e\u5e93\u5bf9\u8c61\u8fd0\u884c\u6570\u636e\u8bbf\u95ee\u5de5\u4f5c\u7684\u6307\u4ee4\u96c6\uff0c\u4ee5INSERT\u3001UPDATE\u3001DELETE\u4e09\u79cd\u6307\u4ee4\u4e3a\u6838\u5fc3\uff0c\u5206\u522b\u4ee3\u8868\u63d2\u5165\u3001\u66f4\u65b0\u4e0e\u5220\u9664\uff0c\u662f\u5f00\u53d1\u4ee5\u6570\u636e\u4e3a\u4e2d\u5fc3\u7684\u5e94\u7528\u7a0b\u5e8f\u5fc5\u5b9a\u4f1a\u4f7f\u7528\u5230\u7684\u6307\u4ee4\u3002
1\u3001\u4e3b\u6761\u76ee\uff1aINSERT\uff0c
INSERT\u662f\u5c06\u6570\u636e\u63d2\u5165\u5230\u6570\u636e\u5e93\u5bf9\u8c61\u4e2d\u7684\u6307\u4ee4\uff0c\u53ef\u4ee5\u63d2\u5165\u6570\u636e\u7684\u6570\u636e\u5e93\u5bf9\u8c61\u6709\u6570\u636e\u8868\u4ee5\u53ca\u53ef\u66f4\u65b0\u67e5\u770b\u8868\u4e24\u79cd\u3002
2\u3001\u4e3b\u6761\u76ee\uff1aUPDATE\uff0c
UPDATE \u6307\u4ee4\u662f\u4f9d\u7ed9\u5b9a\u6761\u4ef6\uff0c\u5c06\u5339\u914d\u6761\u4ef6\u7684\u6570\u636e\u8868\u4e2d\u7684\u6570\u636e\u66f4\u65b0\u4e3a\u65b0\u7684\u6570\u503c\u3002
3\u3001\u4e3b\u6761\u76ee\uff1aDELETE\uff0c
DELETE \u6307\u4ee4\u4e3a\u81ea\u6570\u636e\u5e93\u5bf9\u8c61\u4e2d\u5220\u9664\u6570\u636e\u7684\u6307\u4ee4\u3002
\u6269\u5c55\u8d44\u6599\uff1a
INSERT\u7684\u6ce8\u610f\u4e8b\u9879\uff1a
1\u3001\u63d2\u5165\u7684\u6570\u636e\u5e94\u4e0e\u5b57\u6bb5\u7684\u6570\u636e\u7c7b\u578b\u76f8\u540c\u3002
2\u3001\u6570\u636e\u7684\u5927\u5c0f\u5e94\u5728\u5217\u7684\u89c4\u5b9a\u8303\u56f4\u5185\uff0c\u4f8b\u5982\uff1a\u4e0d\u80fd\u5c06\u4e00\u4e2a\u957f\u5ea6\u4e3a 80 \u7684\u5b57\u7b26\u4e32\u52a0\u5165\u5230\u957f\u5ea6\u4e3a 40 \u7684\u5217\u4e2d\u3002
3\u3001\u5728 values \u4e2d\u5217\u51fa\u7684\u6570\u636e\u4f4d\u7f6e\u5fc5\u987b\u4e0e\u88ab\u52a0\u5165\u7684\u5217\u7684\u6392\u5217\u4f4d\u7f6e\u76f8\u5bf9\u5e94\u3002\u5728 mysql \u4e2d\u53ef\u4ee5\u4f7f\u7528 value\u3002
4\u3001\u5b57\u7b26\u548c\u65e5\u671f\u578b\u6570\u636e\u5e94\u5305\u542b\u5728\u5355\u5f15\u53f7\u4e2d\u3002 MySQL \u4e2d\u4e5f\u53ef\u4ee5\u4f7f\u7528\u53cc\u5f15\u53f7\u505a\u4e3a\u5206\u9694\u7b26\u3002
5\u3001\u4e0d\u6307\u5b9a\u5217\u6216\u4f7f\u7528 null\uff0c\u8868\u793a\u63d2\u5165\u7a7a\u503c\u3002
\u53c2\u8003\u8d44\u6599\u6765\u6e90\uff1a\u767e\u5ea6\u767e\u79d1-DML
SQL语言共分为四大类：数据查询语言DQL，数据操纵语言DML，数据定义语言DDL，数据控制语言DCL。
数据查询语言DQL基本结构是SELECT子句
数据操纵语言DML主要有三种形式：
1) 插入：INSERT
2) 更新：UPDATE
3) 删除：DELETE
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