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常用增删改查sql示例

一、插入数据

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    (1)INSERT INTO Persons VALUES('Gates', 'Bill', 'Xuanwumen 10', 'Beijing')

    (2)INSERT INTO Persons (LastName, Address) 

           VALUES ('Wilson', 'Champs-Elysees'),('Wilson2', 'Champs-Elysees2')

    (3)INSERT INTO Persons select * from Persons2

    (4)SELECT LastName,FirstName INTO Persons_backup FROM Persons

二、删除数据

    (1)DELETEFROM Person WHERE LastName = 'Wilson'

    (2)drop Person

三、修改数据

    (1)UPDATEPerson SETAddress = 'Zhongshan 23', City = 'Nanjing' 

            WHERE LastName = 'Wilson'

    (2)update pset p.Address = 'Zhongshan 23'

    from Person p inner join City c on p.cityId = c.id where c.name = '北京'

四、查询语句

1、普通查询:

    (1)SELECT LastName,FirstName FROM Persons WHERE City='Beijing' 

            ORDER BY Company DESC, OrderNumber ASC

    (2)SELECT DISTINCTCompany FROM Orders 

    (3)SELECT * FROM Persons WHERE (FirstName='Thomas' OR FirstName='William') 

                AND  LastName='Carter'

    (4)SELECT * FROM Persons WHERE LastName IN('Adams','Carter')

    (5)SELECT * FROM Persons WHERE LastName NOT BETWEEN 'Adams' AND 'Carter'

    (6)SELECT TOP 2 * FROM Persons (只sqlserver)

    (7)SELECT * FROM Persons LIMIT 5 (只MySQL)

    (8)SELECT po.OrderID, p.LastName, p.FirstName FROM Persons AS p, 

            Product_Orders AS po WHERE p.LastName='Adams' AND p.FirstName='John'(别名)

    (9)SELECT column_name(s) FROM table_name1 UNION ALL SELECT column_name(s)                     FROM table_name2(合并结果集,union all是直接连接,取到得是所有值,

                记录可能有重复;union 是取唯一值,记录没有重复)

2、like查询

    (1)SELECT * FROM Persons WHERE City LIKE '%' + 'N' + '%'

    (2)SELECT * FROM Persons WHERE City LIKE 'N%'(这种方式可能用到索引)

    (3)SELECT * FROM user where userName like '发_1_2'(_仅替代一个字符)

    (4)SELECT top 10 * FROM user where userId like '[23]%'

            ([charlist]字符列中的任何单一字符,只sqlserver有用)

    (5)SELECT top 10 * FROM user where userId like '[^23]0%'

            ([^charlist]不在字符列中的任何单一字符,只sqlserver有用)

3、关联查询

    SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo FROM Persons

        INNER JOIN Orders ON Persons.Id_P = Orders.Id_P ORDER BY Persons.LastName

    (1)JOIN: 如果表中有至少一个匹配,则返回行

    (2)LEFT JOIN: 即使右表中没有匹配,也从左表返回所有的行

    (3)RIGHT JOIN: 即使左表中没有匹配,也从右表返回所有的行

    (4)FULL JOIN: 只要其中一个表中存在匹配,就返回行

4、分页查询

    (1)SELECT * FROM ceshi limit 0,10(只mysql,从第1个数据开始,取10条数据)

    (2)select top 10 o.* from (select row_number() over(order by userId)as rowNumber,* from             user) as o where rowNumber>0(只sqlserver,从第1个数据开始,取10条数据)

    (3)SELECT * FROM user order by userId  OFFSET 0 ROW FETCH NEXT 10 ROWS ONLY

        (只sqlserver,新版的sqlserver可用,比上一种高效)


四、java写数据库语句需要特别注意的问题

1、SqlServer 对语句的条数和参数的数量都有限制,分别是 1000 和 2100;

2、Mysql 对语句的长度有限制,默认是 4M;

3、where条件中,=与!=两边都不能有null值,否则判断会出错。需要对有null值的字段作比较时,       sqlserver需要用isnull(null,'default_value')把null值转化为默认值再比较;mysql需要用ifnull(null,'default_value')把null值转化为默认值再比较。    


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