sql索引练习
12345678910111213141516171819202122232425262728293031323334CREATE TABLE t_user1(id INT , userName VARCHAR(20),
sql视图练习
1234567891011121314151617181920212223242526272829303132333435363738394041# 创建视图CREATE VIEW v1 AS SELECT * FROM t_book;CREATE VIEW v2 AS SELE
sql合并去重查询练习
123456# 自动去重SELECT id FROM t_book UNION SELECT id FROM t_booktype;# 不去重SELECT id FROM t_book UNION ALL SELECT id FROM t_booktype;
sql给表和字段取别名
123456# 表名 别名SELECT t.bookName FROM t_book t WHERE t.id=1;# 属性名 AS 别名SELECT t.bookName AS bName FROM t_book t WHERE t.id=1;
sql各种连接查询练习
1234567891011121314151617181920212223242526SELECT * FROM t_book,t_bookType;# where那里是两个表的内连接条件SELECT * FROM t_book,t_bookType WHERE t_book.b
sql分组查询配合函数练习
12345678910111213141516171819202122SELECT COUNT(*) FROM t_grade;SELECT COUNT(*) AS total FROM t_grade;SELECT stuName,COUNT(*) FROM t_grade G
sql单表查询练习
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657SELECT id,stuName,age,sex,gradeName
sql触发器练习
1234567891011121314151617181920212223242526272829# 注意使用new和old# 因为是AFTER INSERT，是插入，所以用new代替新插入的那条信息CREATE TRIGGER trig_book AFTER INSERT
sql表操作练习
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647CREATE TABLE t_bookType( id int primary key auto_increm
Ajax练习
1234567891011121314151617181920212223242526272829303132333435363738394041424344 function loadXMLDoc(){ var xmlhttp; if (window.XMLHttpR