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mysql - Simple column change query doesn' work in MySQL 5.7

问题描述

I have an update query created by MySQL Workbench 8 and it looks as follows:

-- MySQL Workbench Synchronization
-- Generated: 2019-12-16 00:30
-- Model: New Model
-- Version: 1.0
-- Project: Name of the project
-- Author: user0

SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='ALLOW_INVALID_DATES';

ALTER TABLE `best_bpgallery`.`k96qw_bpgallery_images` 
CHANGE COLUMN `language` `language` NCHAR(7) CHARACTER SET 'utf8mb4' COLLATE 'utf8mb4_unicode_ci' NOT NULL DEFAULT '*' ;


SET SQL_MODE=@OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;

It looks perfectly fine for me, but when I run it fails:

Executing SQL script in server
ERROR: Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CHARACTER SET 'utf8mb4' COLLATE 'utf8mb4_unicode_ci' NOT NULL DEFAULT '*'' at line 2
SQL Code:
        ALTER TABLE `best_bpgallery`.`k96qw_bpgallery_images` 
        CHANGE COLUMN `language` `language` NCHAR(7) CHARACTER SET 'utf8mb4' COLLATE 'utf8mb4_unicode_ci' NOT NULL DEFAULT '*' 

SQL script execution finished: statements: 3 succeeded, 1 failed

Fetching back view definitions in final form.
Nothing to fetch

I even compared the query to ALTER TABLE documentation and it looks fine for me. So what's going on? What am I missing?

标签： mysqlmysql-workbenchmysql-5.7

解决方案

例如，您必须将 nchar 更改为 varchar。

ALTER TABLE `best_bpgallery`.`k96qw_bpgallery_images` 
CHANGE COLUMN `language` `language` VARCHAR(7) CHARACTER SET 'utf8mb4' COLLATE 'utf8mb4_unicode_ci' NOT NULL DEFAULT '*' ;

nchar 不支持字符集

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