Statement接口提供了三种执行SQL语句的方法:executeQuery 、executeUpdate 和execute 1、ResultSet executeQuery(String sqlString):执行查询数据库的SQL语句,返回一个结果集(ResultSet)对象。 2、int executeUpdate(String sqlString):用于执行INSERT、UPDATE或DELETE语句以及SQL DDL语句,如:CREATE TABLE和DROP TABLE等 (返回...
代码语言:sql 复制 SELECT OBJECT_ID('your_table_name') 代码语言:txt 复制 如果表不存在,此函数将返回NULL。 在使用这些方法时,请确保将your_table_name替换为您要查询的实际表名。 推荐的腾讯云相关产品: 腾讯云SQL Server:产品介绍 腾讯云数据库:产品介绍 腾讯云云数据库MySQL:产品介绍 这些产品都可以提供表...
你可以使用以下SQL语句在SQL Server中创建一个测试表: CREATETABLETestTable(ID uniqueidentifierPRIMARYKEY,Name nvarchar(50))INSERTINTOTestTable(ID,Name)VALUES('2C4E76A0-CE8E-4CB6-80DA-4D9A889DF880','John') 1. 2. 3. 4. 5. 6. 获取字符串 在我们开始转换之前,我们需要从应用程序中获取一个字...
SQL Copy SELECT FirstName, LastName, BaseRate, BaseRate * 40 AS GrossPay FROM DimEmployee ORDER BY LastName; C. Use DISTINCT with SELECT The following example uses DISTINCT to generate a list of all unique titles in the DimEmployee table. SQL Copy SELECT DISTINCT Title FROM DimEmployee...
('语文','1','韩梅梅');INSERTINTO`choose_course`VALUES('语文','1','露西');INSERTINTO`choose_course`VALUES('语文','2','莉莉');INSERTINTO`choose_course`VALUES('语文','2','格林');INSERTINTO`choose_course`VALUES('数学','1','李雷');INSERTINTO`choose_course`VALUES('数学','1','名字...
VALUES(1002,'Tom'); #字符串、日期时间类型的变量需要使用一对''表示 INSERT INTO emp VALUES(1003,'Jerry'); # SELECT * FROM emp\G SHOW CREATE TABLE emp\g 4. 导入现有的数据表、表的数据。 方式1:source 文件的全路径名 举例:source d:\atguigudb.sql; 方式2:基于具体的图形化界面的工具可以导...
SQL SELECTFirstName, LastName, BaseRate, BaseRate *40ASGrossPayFROMDimEmployeeORDERBYLastName; C. Use DISTINCT with SELECT The following example usesDISTINCTto generate a list of all unique titles in theDimEmployeetable. SQL SELECTDISTINCTTitleFROMDimEmployeeORDERBYTitle; ...
SQL Distinct So far we have used the select statement to retrieve all the records in a table regardless if some values repeat or not. If you wish, you can use the DISTINCT keyword to remove duplicates from your results. For instance if you wanted to just return a unique list of employees...
SQL Script: Column Alias Copy SELECT EmpId "Employee Id", FirstName AS Name FROM Employee; The above query will display the following result. + Operator in SELECT Statement The+operator in MS SQL Server concatenates string values or adds numeric values. The following concatenates twovarcharcolumns...
1 2 3 Select UNIQUE column from table Here, the column is the name of the column from which you want to fetch unique values the table is the name of the table on which the above query is being executed SQL SELECT DISTINCT The SQL SELECT DISTINCT is ANSI standard SQL statement tha...