In PostgreSQL, you can easily retrieve the row count for each table in a database. This can be particularly useful for database analysis, monitoring, or reporting. There are a couple of methods to accomplish this, using either SQL queries that interact with PostgreSQL’s system catalog or by...
在PostgreSQL中,虽然没有内置的FIND_IN_SET函数(该函数在MySQL中常用),但我们可以通过自定义函数来实现类似的功能。下面是对findinset(这里我们称之为find_in_set,以保持命名的一致性)的详细解释和使用示例。 1. findinset(find_in_set)的含义及其用途 find_in_set函数用于在一个逗号分隔的字符串中查找指定字符...
Deleting duplicate rows from a table is a little bit tricky. Finding and deleting duplicate rows is pretty easy if the table has a limited number of records. However, if the table has enormous data, then finding and deleting the duplicates can be challenging. PostgreSQL provides multiple ways ...
table_close(relation,AccessShareLock); /* If we found more than one child, sort them by OID. This ensures reasonably consistent behavior regardless of the vagaries of an indexscan. This is important since we need to be sure all backends lock children in the same order to avoid needless dea...
补充:PostgreSQL 行转列、列转行字符串函数、字符串分割函数 本文主要介紹PostgreSQL 的行转列、列转行以及字符串切割函数,实际业务中对前两个均有使用,并配有实际例子参考。 1、字符串列转行 string_agg,某些地方也称为字符串聚合操作。 如果需要按照一个字符串按照某个分割符拼接起来。
1 ALTER TABLE your_table_name 2 ADD COLUMN tags text[]; This adds a tags column that can store an array of strings. How to Find One or More Elements in a PostgreSQL Array Time to discover the most effective PostgreSQL find in array approaches! The following queries will be executed usi...
table_name SET column_name = REPLACE(column,old_text,new_text) WHERE condition Let's use thecustomertable in the sample database to demonstrate: SELECT first_name, last_name, email FROM customer; Now, suppose you want to update e-mail columns withzhaoxinsoft.comreplacement fieldsakilacustomer...
Do table names in your database always make sense? Honestly. Yeah, ours neither. See what we did about that. Learn now Query selecttable_schema, table_namefrominformation_schema.tableswheretable_name ~'[0-9]'andtable_schemanotin('information_schema','pg_catalog')andtable_type ='BASE TABL...
Learn how to find slow queries in PostgreSQL using logs and metrics. Tutorial on how to check for and fix performance issues to speed up your database.
create table cards ( id INT, name VARCHAR(50), planeswalker BOOLEAN, signature_spell BOOLEAN ); insert into cards (id, name, planeswalker, signature_spell) values (1, 'Norby', false, true),(2, 'Johanna', true, false), (3, 'Killian', false, true), (4, 'Madalyn', f...