文章目录 示例 解释 一条select语句在MySQL中的奇幻之旅 示例 explain select * from emp; 解释 列(Column) 含义(Meaning) id The SELECT...如存在子查询或者联合查询这个编号会自增。 type:此列是在优化SQL语句时最需要关注的列之一,此列显示了查询使用了何种类型。...语句为value IN (SELECT primary_key ...
Title: Meaning Read Only: true Maximum Length: 80 Category of the development library goal. GoalExternalId: string Title: External ID Maximum Length: 30 Unique external identifier for the library goal. GoalId: integer (int64) Title: Content Item ID Unique identifier for the library g...
This is the hash key of the attributes which make up the composite key for the Check-In Documents resource and used to uniquely identify an instance of Check-In Documents. The client should not generate the hash key value. Instead, the client should query on the Check-In Doc...
Efficiency and Atomicity: Updating multiple columns in a single query improves database performance by reducing the number of operations the database engine needs to process. This improves efficiency and also atomicity, meaning all updates succeed together or none are applied, preserving data consistency...
“Unable to enlist in the transaction” with Oracle linked server from MS SQL Server [<Name of Missing Index, sysname,>] in non clustered index [Execute SQL Task] Error: The value type (__ComObject) can only be converted to variables of type Object. [ODBC Driver Manager] Data source nam...
Flag indicating whether the body request is JSON (header Content-Type = application/json), meaning its a Form URL encoded request (header Content-Type = application/x-www-form-urlencoded). password object The password queryParameters object The custom query parameter we want to add once we...
Update rules get applied by the rule system when the result relation and the command type of a query tree are equal to the object and event given in theCREATE RULEcommand. For update rules, the rule system creates a list of query trees. Initially the query-tree list is empty. There ca...
Deprecation refers to the stage in the product lifecycle when a feature or functionality is no longer in active development and may be removed in future releases. Each release of Windows Server adds new features and functionality; we also occasionally remove features and functionality, ...
Either the Oracle database doesn't allow you to write, or you set the foreign server option isolation_level to read_only. Author chrisbitmead commented Nov 21, 2024 OK... how about you document that, because "read only" has no conventional meaning in the context of isolation levels, it...
Version 2: can be ignored as it was only used in early alpha versions of MySQL 4.1.x and won't be documented here. Version 3: added the relay logs and changed the meaning of the log position. Version 4: added the FORMAT_DESCRIPTION_EVENT and made the protocol extensible. ...