错误代码 [1068] [42000] 是一个 SQL 错误,具体表示“multiple primary key defined”,即“定义了多个主键”。这个错误通常发生在尝试为一个表设置超过一个主键时。 2. 阐述“multiple primary key defined”错误的产生原因 “multiple primary key defined”错误产生的原因是在一个表中尝试定义了多个主键。在 SQL...
tmptable1 select * from another_table; -- OK mysql> alter table tmptable1 add primary key (`IDPersoane`); -- ERROR: Multiple primary key defined, ErrorNo 1068 mysql> show create table tmptable1; # `my_row_id` bigint unsigned NOT NULL AUTO_INCREMENT /*!80023 INVISIBLE */, # `ID...
【示例】使用ALTERTABLE语句在已存在的表中添加主键约束 alter table lemon_student add primary key(id, name); 执行结果如图所示 可以看到,通过修改表的语句“ALTER TABLE”可以在已存在的表中添加主键约束, 但需要注意的是在添加主键约束之前,表中不能存在主键,否则会提示“Multiple primary key defined”的错误。
SQL_MAX_CONCURRENT_ACTIVITIES(ODBC 1.0) An SQLUSMALLINT value that specifies the maximum number of active statements that the driver can support for a connection. A statement is defined as active if it has results pending, with the term "results" meaning rows from a SELECT operation or rows...
· 错误:1068 SQLSTATE: 42000 (ER_MULTIPLE_PRI_KEY) 消息:定义了多个主键。 · 错误:1069 SQLSTATE: 42000 (ER_TOO_MANY_KEYS) 消息:指定了过多键:允许的最大键数是%d。 · 错误:1070 SQLSTATE: 42000 (ER_TOO_MANY_KEY_PARTS) 消息:指定了过多键部分:允许的最大键部分是%d。 · 错误:...
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A computed column can be used as a key column in an index or as part of any PRIMARY KEY or UNIQUE constraint, if the computed column value is defined by a deterministic expression and the data type of the result is allowed in index columns. For example, if the table has integer columns...
ALTER TABLE statement conflicted with the FOREIGN KEY constraint Alternative to using multiple REPLACE statements AlwaysUseDefaultCodePage: Can I change the default to True? An error occurred during local report processing. (Microsoft.ReportViewer.WinForms) An error occurred in the requested FTP operatio...
- A primary key can’t be created on a null able column wherein a unique key can be created on a null able column. - There can be only one primary key on a table wherein a table can have multiple unique key defined on it. ...