在MySQL中,我们可以使用IF EXISTS子句来判断数据库是否存在。这样,如果数据库存在,就执行某个操作;否则,就不执行。 以下是一个使用IF EXISTS子句的示例: IFEXISTS(SELECTSCHEMA_NAMEFROMINFORMATION_SCHEMA.SCHEMATAWHERESCHEMA_NAME='mydatabase')SELECT'Database exists.';ELSESELECT'Database does not exist.'; 1....
$check = $connect->execute("SELECT * FROM information_schema.schemata WHERE schema_name='".$database."'"); if (!$check && !$connect->execute("CREATE DATABASE IF NOT EXISTS `".$database."` default collate utf8_general_ci ")) { return resultArray(['error' => '没有找到您填写的数...
What I am trying to do is create some code which will allow me to check if a table of a certain name exists in a database. If the table DOES exist, then I want the code to then insert values into the table. If the table does not exist, then the table should be created, and ...
Therefore, we can check the exit status for determining whether the database exists or not in a shell script: $ result=$(mysql -u user -e "use students") $ if [[ $result -eq 0 ]] then echo "The database exists" else echo "The database doesn’t exist" fi 2.2. Using the show...
if not exists 数据库名; 查看所有数据库 show databases; 切换数据库 use 数据库名; 删除数据库 drop database if exists 数据库名; 修改数据库编码 alter database 数据库名 character set utf8; 表结构常用操作操作 语句创建表 create table if not exists 表名(字段名 数据类型, 字段名 数据类型, ......
"Can't create database '%-.64s'; database exists", #define ER_DB_DROP_EXISTS 1008 "Can't drop database '%-.64s'; database doesn't exist", #define ER_DB_DROP_DELETE 1009 "Error dropping database (can't delete '%-.64s', errno: %d)", ...
1 . 数据库创建 : Create database db_name; 数据库删除 : Drop database db_name; 删除时可先判断是否存在,写成 : drop database if exits db_name 2 . 建表 : 创建数据表的语法 : create table table_name (字段1 数据类型 , 字段2 数据类型); ...
` -- Current Database:hellodb` `` -- `` CREATE DATABASE /*!32312 IF NO T EXISTS/ hellodb /!40100 DEF AULT CHARACTER SET utf8 */; `` +---+---+ [(2)二进制全备] [ 方法一: 导出二进制日志文件内容] +---+---+ | 1 |[root@stu18 data]...
c# Check registry if program is installed if yes get install location ? C# Check to make sure first character in a string is a letter C# check username if already exists from database C# Class - USB Port Enabled/Disabled Status Detection C# class for JSON is resulting a Null Reference Exc...
create database 库名 create database if not exists 库名 alter rename database 旧库名 to 新库名 alter database 库名 character set 新字符集 drop drop database 库名 drop database if exists 库名 表的管理 create create table 表名 ( 列名 列类型 约束) alter # 修改列名 alter table 表...