对于LIKE和正则表达式搜索，请记住，没有可提取三元组的模式将退化为全索引扫描。这意味着，索引/位图索...
I was wondering if it's possible to do a query using the IN clause where the options inside it are LIKE clauses, for example I have my existing SQL which returns the same results as I intend it just seems like a round about way to do it.SELECT * FROM pg_stat_activity WHERE applica...
Not-null constraints are always copied to the new table. CHECK constraints will be copied only if INCLUDING CONSTRAINTS is specified. Indexes, PRIMARY KEY, and UNIQUE constraints on the original table will be created on the new table only if the INCLUDING INDEXES clause is specified. No distinct...
PRIMARY KEY, and UNIQUE constraints on the original table will be created on the new table only if the INCLUDING INDEXES clause is specified. No distinction is made between column constraints and table constraints.
This will return only the names that start with the lowercase letterj. You may recognize that this is different than other SQL dialects, like PostgreSQL, which usesILIKEfor case-insensitive matching. Here's an example of using theLIKEclause to search for a pattern within a single column: ...
规范化您的设计，并将数组解嵌套到单独的表中，每行一个元素。然后用COLLATE "C"或SP-GiST索引创建一...
规范化您的设计，并将数组解嵌套到单独的表中，每行一个元素。然后用COLLATE "C"或SP-GiST索引创建一...
The LIKE clause specifies a table from which the new table automatically copies all column names, their data types, and their not-null constraints. 如上所示,当使用LIKE子句做表复制时,默认会自动拷贝所有字段、字段类型以及它们的NOT-NULL约束,这也就解释了刚才为什么会成功复制NOT-NULL约束。
PostgreSQL: % - Any string of zero or more characters. _ - Any single character ESCAPE clause E.g. %30!%%' ESCAPE '!' will evaluate 30% as true ANSI SQL92: % _ An ESCAPE character only if specified. PostgreSQL also has the SIMILAR TO operator which adds the following: [specifier] ...
PostgreSQL LIKE查询性能变化 关于对数据库中特定表的 LIKE 查询的响应时间,我看到了相当大的变化。有时我会在200-400毫秒内得到结果(非常可接受),但有时候返回结果可能需要30秒。 我知道 LIKE 查询是非常耗费资源的,但我不明白为什么响应时间会有这么大的差异。我在...