[MSSQL]SQL常用语句。用到就更新

SQL常用语句

创建表

CREATE TABLE [表名] (
	字段名 数据类型 [NOT NULL] [PRIMARY KEY],
	字段名 数据类型 [NOT NULL] [PRIMARY KEY]
)

添加字段默认值

ALTER TABLE [table_global_system_basic_module_yogurtcry_20201007]
ADD DEFAULT (-1) FOR dataState

添加字段说明

EXEC sp_addextendedproperty 'MS_Description', '需要添加的说明', 'user', dbo, 'table', [表名], 'column', [列名]

避免重复写入数据

INSERT INTO [表名]
(
    字段名1,
    字段名2,
    字段名3,
    字段名4
)
SELECT
    '要插入的数据1',
    '要插入的数据2',
    '要插入的数据3',
    '要插入的数据4'
WHERE NOT EXISTS
(
    SELECT
        字段名1,
        字段名2,
        字段名3,
        字段名4
    FROM [表名]
    WHERE [表名].要比对的字段名 = '要比对的数据'
);

创建唯一值约束(非主键)

ALTER TABLE [表名]
ADD CONSTRAINT [约束名] UNIQUE (字段名)

删除唯一值约束

ALTER TABLE [表名]
DROP CONSTRAINT [约束名]

查询数据库中表内总行数

SELECT
    table_tableNameList.name AS 表名,
    table_tableRowCount.rows AS 表内行数
FROM (
    SELECT
        name,
        id,
        xtype
    FROM sysobjects
    WHERE sysobjects.xtype = 'u'
) AS table_tableNameList
LEFT JOIN (
    SELECT
        id,
        rows
    FROM sysindexes
    WHERE indid IN (0, 1)
) AS table_tableRowCount ON table_tableNameList.id = table_tableRowCount.id
ORDER BY 表名 ASC, 表内行数 DESC

查询数据库中表内总行数及字段名

SELECT
    table_tableRowCountInfo.name AS 表名,
    table_columnName.COLUMN_NAME AS 字段名,
    table_tableRowCountInfo.rows AS 表内行数
FROM (
    SELECT
        table_tableNameList.name,
        table_tableRowCount.rows
    FROM (
        SELECT
            name,
            id,
            xtype
        FROM sysobjects
        WHERE sysobjects.xtype = 'u'
    ) AS table_tableNameList
    LEFT JOIN (
        SELECT
            id,
            rows
        FROM sysindexes
        WHERE indid IN (0, 1)
    ) AS table_tableRowCount ON table_tableNameList.id = table_tableRowCount.id
) AS table_tableRowCountInfo
LEFT JOIN (
    SELECT *
    FROM INFORMATION_SCHEMA.COLUMNS
) AS table_columnName ON table_columnName.TABLE_NAME = table_tableRowCountInfo.name