AI代码解释 mysql>create tabletest1(a int notnullcomment'字段a');QueryOK,0rowsaffected(0.01sec)mysql>insert into test1values(null);ERROR1048(23000):Column'a'cannot benullmysql>insert into test1values(1);QueryOK,1row
When inserting a new row, the default value for a column with an expression default can be inserted either by omitting the column name or by specifying the column asDEFAULT(just as for columns with literal defaults): mysql>CREATETABLEt4(uidBINARY(16)DEFAULT(UUID_TO_BIN(UUID()));mysql>INSER...
增加表字段:ALTER TABLE tablename ADD [COLUMN] column_definition [FIRST | AFTER col_name] alter table [emp] add column [age] [int(3)]; 删除表字段:ALTER TABLE tablename DROP [COLUMN] col_name 字段改名:ALTER TABLE tablename CHANGE old_col_name column_definition [FIRST|AFTER col_name] 注...
CHANGE [COLUMN] oldcolname newcolname type [CHARSET [=] charset] [COLLATE[=]collation] [[NOT]NULL] [DEFAULTvalue] [FIRST|{AFTER colname}] 删除字段: ALTERTABLEtablename DROP[COLUMN] colname 添加外键: ALTERTABLEtablename ADDCONSTRAINTfknameFOREIGNKEY (colname[, ...]) REFERENCEStablename2(col...
I have a query with a SELECT statement ... I would love to add a new column with a static value for all records, past and future. So, given this [simple] query ... select a, b, c from table1 ; +---+---+---+ | a | b | c | +---+---+---+ | 1 | 2 | 3...
ALTERTABLEuserADDINDEX((MONTH(create_time))); 通过函数索引也可以很方便提高我们的查询效率。具体使用可以查看如下链接 https://dev.mysql.com/doc/refman/8.0/en/create-index.html demo链接 https://github.com/lyb-geek/springboot-learning/tree/master/springboot-mysql-virtual-column...
fieldvalue = ws.cell(row=row, column=col).value fielddesc = ws.cell(row=row, column=col + 1).value # add alter table statement # skip fielddesc None if fielddesc is None or str(fielddesc).strip() == '': continue # add alter table statement ...
setDefaultValue() Sets the column's default value setInlineSize() Sets the inline size for a blob column (not applicable to columns not of blob types) setLength() Sets the column's length setName() Sets the column's name setNullable() Toggles the column's nullability setPartitionKey() ...
表:table,行:row 列:column 索引:index 视图:view 存储过程:procedure 存储函数:function 触发器:trigger 事件调度器:event scheduler,任务计划 用户:user 权限:privilege SQL语句分类 DDL: Data Defination Language 数据定义语言 CREATE,DROP,ALTER DML: Data Manipulation Language 数据操纵语言 ...
修复内核版本从8.0.1升级到8.0.2后,带有二级分区的分区表无法执行增加列(ADD COLUMN)操作的问题。 修复谓词条件中存在DEFAULT表达式时,并行查询可能导致的集群崩溃问题。 修复DLM策略执行时权限过高的问题。 修复归档表在存在降序索引时进行归档操作失败的问题。 修复对Blob列进行更新时,原记录的Blob空间无法回收的问题...