使用GROUP_CONCAT函数:这是MySQL中常用的方法,可以将同一组的多行数据合并为一个字符串。 使用STRING_AGG函数:在某些版本的MySQL中,可以使用STRING_AGG函数来实现类似的功能。 自定义SQL查询:通过自定义SQL查询,可以实现更复杂的多行合并逻辑。 应用场景 生成报告:在生成报表时,可能需要将多行数据
SELECT CONCAT('UPDATE ', a.table_name, 'set sku_name = "IPHONE 13PRO" where sku_id = 1106;') FROM information_schema.columns a, information_schema.columns b WHERE a.table_name = b.table_name and a.table_schema = 'db_lingyejun' and a.column_name='sku_id' and b.table_schema =...
增加多个字段:alter table tabelName add column fieldName1 dateType,add columns fieldName2 dateType; 多行命令输入:注意不能将单词断开;当插入或更改数据时,不能将字段的字符串展开到多行里,否则硬回车将被储存到数据中; 增加一个管理员帐户:grant all on.to user@localhost identified by “password”; 每...
columns_priv:id,name #该表放行的权限,针对:某一个字段 GRANT 权限1,...,权限n ON 数据库.* TO 用户名@IP地址 ·权限、用户、数据库 ·给用户分派在指定的数据库上的指定的权限 GRANT ALL ON 数据库.* TO 用户名@IP地址; ·给用户分派指定数据库上的所有权限 grant all on *.* to "egon1"@"loc...
命令:show full columns tables_name;**作用: **显示表中所有列信息。 例子: mysql> show full columns from t_base_data\G; *** 1\. row *** Field: id Type: bigint(20) Collation: NULL Null: NO Key: PRI Default: NULL Extra: auto_increment ...
| COLUMNS | | COLUMN_PRIVILEGES | | ENGINES | | EVENTS | | FILES | | GLOBAL_STATUS | | GLOBAL_VARIABLES | | KEY_COLUMN_USAGE | | OPTIMIZER_TRACE | | PARAMETERS | | PARTITIONS | | PLUGINS | | PROCESSLIST | | PROFILING | | REFERENTIAL_CONSTRAINTS | ...
Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 65,535. The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used. ...
{return false;}//获取主表结构列信息List<ColumnInfo> masterColumns = configExtMapper.getColumnInfoList(masterTable);if (masterColumns.isEmpty()){return false;}String alterName = null;for (ColumnInfo column: masterColumns) {column.setAlterName(alterName);alterName = column.getColumnName();}for(...
SELECT columns_name, ··· FROM table_name, ··· [WHERE ···], [UNION ···], [GROUP BY ···], [HAVING ···], [ORDER BY ···]; 详解: select [all | distinct] select_expr from ->where->group by[合计函数] ->having->order by ->limit 其中 1.1、select_expr a、计...
ndb_blob_tool — Check and Repair BLOB and TEXT columns of NDB Cluster Tables ndb_config — Extract NDB Cluster Configuration Information ndb_delete_all — Delete All Rows from an NDB Table ndb_desc — Describe NDB Tables ndb_drop_index — Drop Index from an NDB Table ndb_drop_table...