SELECT column_name FROM table_name WHERE column_name NOT IN (SELECT column_name FROM another_table) 注意,"NOT IN"操作符在使用时需要确保子查询的结果集不包含NULL值,否则可能导致不符合预期的结果。 "NOT EXISTS": "NOT EXISTS"操作符用于判断子查询的结果集是否为空,如果为空,则返回真(True)。它通...
TheNOT INoperator in SQL is used to fetch all the records that aren’t present based on a particular field. We can use this operator to select records from one table that aren’t present in another table: SELECT * FROM Course c WHERE c.id NOT IN ( SELECT r.course_id FROM Registratio...
代码:SELECT `username`,citytable.cityid FROM `usertable`,`citytable` WHERE usertable.cityid=citytable.cityid在FROM子句中可用以下两种格式为表或视图指定别名: 代码:表名 as 别名 表名 别名例如上面语句可用表的别名格式表示为: 代码:SELECT `username`,b.cityid FROM usertable a,citytable b WHERE a...
-- copy contents of a table to another database SELECT * INTO CustomersCopy IN another_db.mdb FROM Customers; Here, the SQL command copies the Customers table to the CustomersCopy table in the another_db.mdb database. Note: The user must have WRITE privilege to copy data to a table in...
SELECT --从数据库表中检索数据行和列 INSERT --向数据库表添加新数据行 DELETE --从数据库表中删除数据行 UPDATE --更新数据库表中的数据 --数据定义 CREATE TABLE --创建一个数据库表 DROP TABLE --从数据库中删除表 ALTER TABLE --修改数据库表结构 ...
You can use SELECT FROM statement to retrieve data from this table, then use an INSERT INTO to add that set of data into another table, and two statements will be nested in one single query.
How to SELECT data from a table which is not present in another table with SQL is a common operation in databases. There are many ways to query this, like usingNOT IN andNOT EXISTS. But the most efficient way is to useLEFT JOIN. ...
SELECTstor_id,qtyFROM(SELECTstor_id,qtyFROMsalesWHEREqty>50)AStemp_table;2、UNION UNION运算符从...
SELECT * INTO CustomersBackup2017 FROM Customers; The following SQL statement uses the IN clause to copy the table into a new table in another database:SELECT * INTO CustomersBackup2017 IN 'Backup.mdb' FROM Customers; The following SQL statement copies only a few columns into a new table:...
SELECT TOP 5 a.BusinessEntityID, a.Rate INTO #tempTop5Paychecks -- dump to temporary table FROM HumanResources.EmployeePayHistory a INNER JOIN HumanResources.Employee b ON a.BusinessEntityID = b.BusinessEntityID WHERE b.OrganizationNode.GetLevel() > 1 -- do not include executives or C leve...