根据这个查询，emp 是父表，bonus 是子表，因为后者sales.empid(+)] 与前连接外连接。因此，Oracle将emp作为驱动表，bonus 作为被驱动表，尽管后者比前者小。这就是cost 不是决定性因素，而连接条件( join condition)是hash outer join 的决定性因素的原因。假设Oracle可以在RAM分配的内存空间（由全局参数HASH_ARE...
CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ... ELSE result END 常见问题及原因 当你在使用 CASE 语句时,如果缺少了右括号,Oracle 数据库会抛出语法错误。这是因为 SQL 语句需要成对的括号来定义语句的边界。 解决方法 确保每个 CASE 语句都有匹配的左括号和右括号。以下是一个正确的 ...
JOIN ON条件中的Oracle SQL Case语句虽然在连接中可以使用case表达式，但在这里实际上并不需要，可以使用...
Performance – the database stops processingcasewhen it finds the firsttruecondition. Ordering the clauses so the most likely are at the top can make the expression faster. In most cases, this benefit is tiny so only worth considering when speed is critical. With yourcaseexpression in hand...
JOIN ON条件中的Oracle SQL Case语句虽然在连接中可以使用case表达式，但在这里实际上并不需要，可以使用...
7. case when 和 decode 知识准备 1. sql执行过程 1)执行过程 当一个oracle实例接收到一条sql后,执行过程如下: 1) create a cursor 创建游标 2) parse the statement 分析语句 3) describe results of a query 描述查询的结果集 4)define output of a query 定义查询的输出数据 ...
A view is an Oracle data structure defined through a SQL statement. The SQL statement is stored in the database. When you use a view in a query, the stored query is executed and the base table data is returned to the user. Views do not contain data, but represent ways to look at ...
A problem is fixed where a segmentation fault could occur during a query that contained aCASEstatement and aGROUPBYclause. (BugDB #28448399) A problem that caused a delay in a log-based catchup (LBCU) operation is fixed. (BugDB #28852175) ...
Track, trace, and monitor the condition of products Quickly deploy with preintegrated blockchain Connect to other applications and data sources Tamper-resistant blockchain tables in Oracle Database Database fraud protection with blockchain technology. Tamper-proof features maintain and safeguard centralized...
PostgreSQL Update Statement with Join What about PostgreSQL? In this case, the same concepts that work in SQL Server do the job also on PostgreSQL. We have just a few differences with the syntax as we do not specify the join. But we use the old join syntax with the WHERE clause. ...