The following SQL statement will update the contactname to "Juan" for all records where country is "Mexico":Example UPDATE Customers SET ContactName='Juan' WHERE Country='Mexico'; Note: Be careful when updating
INSERT INTO employees (name, position) VALUES ('John Doe', 'Developer'); 2.3 UPDATE语句 (UPDATE Statement) UPDATE语句用于更新表中已有的数据。基本语法如下: UPDATE table_name SET column1 = value1 WHERE condition; 例如,更新“employees”表中某个员工的职位: UPDATE employees SET position = 'Senior...
UPDATEtable_name SETcolumn1=value1,column2=value2, ... WHEREcondition; Note:Be careful when updating records in a table! Notice theWHEREclause in theUPDATEstatement. TheWHEREclause specifies which record(s) that should be updated. If you omit theWHEREclause, all records in the table will be...
SQL Quick Reference From W3Schools« Previous Next Chapter » SQL StatementSyntax AND / OR SELECT column_name(s) FROM table_name WHERE condition AND|OR condition ALTER TABLE ALTER TABLE table_name ADD column_name datatype or ALTER TABLE table_name DROP COLUMN column_name AS (alias) ...
W3Schools SQL QuizSQL QUIZPoints: 25 out of 25 1. What does SQL stand for? You answered: Structured Query Language Correct Answer! 2. Which SQL statement is used to extract data from a database? You answered: SELECT Correct Answer! 3. Which SQL statement is used to update data in ...
SQL StatementSyntax AND / OR SELECT column_name(s)FROM table_nameWHERE conditionAND|OR condition ALTER TABLE ALTER TABLE table_name ADD column_name datatype or ALTER TABLE table_name DROP COLUMN column_name AS (alias) SELECT column_name AS column_aliasFROM table_name or SELECT column_name...
Without parenthesis, the select statement will return all customers from Spain that starts with a "G", plus all customers that starts with an "R", regardless of the country value:Example Select all customers that either: are from Spain and starts with either "G", or starts with the letter...
You should probably change your update statement so that it cannot try to change the value of your Primary Key to a value that already exists in the table. Either that, or catch the error and alert the user that they cannot choose the values that caused the error....
Statement角色 Statement 的功能在于根据传入的sql语句,将传入sql经过整理组合成数据库能够识别的sql语句(对于静态的sql语句,不需要整理组合;而对于预编译...其遍历结果集的基本形式如下: while(resultSet.next()) { //传入列明或者列索引获取记录中对应列的值 resultSet.getXXX(param...boolean last() 将光标移动...
SQL Tutorial——w3schools (示例教程)入门之后,就要多学学T-SQL语言了。除了51自学网的SQL Server数据库教程外,w3schools是一个很好的资源库,它不止讲解T-SQL语言的知识点,还有一个在线的示例数据库提供给用户,可以随时随地进行练习。 Head First SQL——Head First系列(文字教程)因为是文字教程,所以贴的是豆瓣...