SELECT * FROM Websites WHERE name IN ('Google','菜鸟教程'); 1. 2. IN 与 = 的异同 相同点:均在WHERE中使用作为筛选条件之一、均是等于的含义 不同点:IN可以规定多个值,等于规定一个值 IN SELECT column_name(s) FROM table_name WHERE column_name IN (value1,va
Example: SQL SELECT All SQL SELECT WHERE Clause ASELECTstatement can have an optionalWHEREclause. TheWHEREclause allows us to fetch records from a database table that matches specified condition(s). For example, -- select all columns from the customers table with last_name 'Doe'SELECT*FROMCust...
Example Select all customers with a CustomerID greater than 80: SELECT * FROM Customers WHERE CustomerID > 80; Try it Yourself » The following operators can be used in the WHERE clause:OperatorDescriptionExample = Equal Try it > Greater than Try it < Less than Try it >= Greater than...
一、查找重复记录 1.查找全部重复记录 Select * From 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1) 2.过滤重复记录(只显示一条) Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title) 注:此处显示ID最大一条记录 二、删除重复记录 1....
Select * from STRING_SPLIT(@FirstNamesList, ',') Copy If you execute the above query, we get the following result as expected. Using STRING_SPLIT with IN Clause Declare @FirstNamesList nvarchar(100) = 'Mark,John,Sara' SELECT * FROM Employees where FirstName IN (SELECT * FROM STRING_...
8.2.1.1 WHERE Clause Optimization 包含select、delete、update中的where子句 At one time, a scan was used based on whether the best index spanned more than30%of the table, but a fixed percentage no longer determines the choice between using an index or a scan. The optimizer now is more compl...
在DML语句里的内联视图(in-line view),例如 nsert into (<selectclause>) values (...),其具体示例如下: insert into (selectobject_id,object_name,object_typefromxxxwhereobject_id<1000) values(1001,'testbyhao','testtype'); 普通视图 我们平时说的视图指的是create view语句创建的视图类型,我们暂且称...
1 一个 SQL 语句中的 select_expression 或 where_definition 可由任何使用了下面所描述函数的表达式组成...
select * from emp,dept; 1. 2. 2.2 如何清除笛卡尔积现象的影响 我们发现不是所有的数据组合都是有用的,只有 员工表.dept_id = 部门表.id 的数据才是有用的。所以需要通过条件过滤掉没用的数据。 -- 设置过滤条件 Column 'id' in where clause is ambiguous ...
The SQL SELECT Statement can be used with the SQL WHERE Clause to filter records based on requirements. For example, the below SQL SELECT Statement will return “employee_name” and “Salary” of employees working in “Sales” department from the employee table. ...