ALTERTABLEtable_nameMODIFYCOLUMNcolumn_nameVARCHAR(255)CHARACTERSETcharset_name; 1. 2. 在这个示例中,table_name是表名,column_name是要修改的字段名,charset_name是要修改成的字符集名。 假设我们有一个名为users的表,其中有一个字段username,我们想要将其字符集修改为utf8mb4,我们可以这样做: ALTERTABLEusers...
mysql> alter table emp drop column age; 1. 字段改名, age 改为 age1 alter table emp change age age1 int(4); 1. change和modify都可以修改表的定义,不同的是change后面需要些两次列名,不方便,但是change的有优点是可以修改列名称,modify不可以。 修改字段排序 增加新字段birth类型是date 到ename后面 my...
alter table t1 convert to character set gbk collate gbk_bin; --提示Records: 112345678910111213141516 4 column的character_set指定/修改 -- 套路相同 alter table add c1 varchar(50) character set gbk collate gbk_bin; alter table t1 change c1 c1 varchar(50) character set gbk collate gbk_bin;...
A special case occurs if you have old tables from before MySQL 4.1 where a nonbinary column contains values that actually are encoded in a character set different from the server's default character set. For example, an application might have stored sjis values in a column, even though MySQL...
MySQL chooses the column character set and collation in the following manner: If both CHARACTER SET charset_name and COLLATE collation_name are specified, character set charset_name and collation collation_name are used. CREATE TABLE t1 ( col1 CHAR(10) CHARACTER SET utf8mb4 COLLATE utf8mb4...
To convert a binary or nonbinary string column to use a particular character set, use ALTER TABLE. For successful conversion to occur, one of the following conditions must apply: If the column has a binary data type (BINARY, VARBINARY, BLOB), all the values that it contains must be encode...
CHANGE 旧列名 新列名 data_type NOT NULL DEFAULT ''; ④删除列—— ALTER TABLE table_name DROP column, DROP column ...; PS : ①修改表名—— RENAME TABLE 旧表名 TO 新表名; ②修改表字符集—— ALTER TABLE 表名 CHARACTER SET 字符集; ...
ALTER TABLE 表名 MODIFY [column] 字段名1 字段类型 [DEFAULT 默认值] [FIRST|AFTER 字段名2]; 对默认值的修改只影响今后对表的修改 删除现有表中的列 ALTER TABLE 表名 DROP [column] 字段名; 重命名现有表中的列 ALTER TABLE 表名 CHANGE [column] 列名 新列名 新数据类型; 5. 重命名表 方式一:使...
在创建表时指定character set的语法如下: CREATE TABLE table_name ( column_name VARCHAR(255) CHARACTER SET utf8, ... ); 复制代码 在连接数据库时指定character set的语法如下: SET NAMES 'utf8'; 复制代码 通过正确设置character set,可以确保数据库中的数据能够正确显示和处理不同语言的字符集,从而提高数...
-- 批量修改所有表的默认字符集SELECTCONCAT('ALTER TABLE ',table_name,' DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;')AS_sqlFROMinformation_schema.`TABLES`WHERETABLE_SCHEMA='db_name';-- 批量修改所有字段的字符集SELECTCONCAT('ALTER TABLE ',table_name,' MODIFY ',column_name,' ...