多行转一行 string_agg(text,text) 查询字段只能是字符型 结果用“,”隔开 SELECT , a.db_name, string_agg(b.username, ',') FROM tbl_company a, tbl_user b WHERE = b.company_id group by ; 1. 一行拆分为多行 regexp_split_to_table(string, pattern) 查找子字符串的位置 position(substring ...
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Data School wants a comprehensive post with visuals to help people understand how to find duplicates in a table with SQL. Please use stack overflow to understand the many variations: https://stackoverflow.com/questions/3327312/how-can-i-drop-all-the-tables-in-a-postgresql-database...
在PostgreSQL中,可以使用ALTER TABLE语句来删除一个表的列。以下是一个示例: 代码语言:sql 复制 ALTER TABLE table_name DROP COLUMN column_name; 其中,table_name是要删除列的表的名称,column_name是要删除的列的名称。 注意:在删除列之前,请确保已经备份了数据库,以防止意外删除数据导致的数据丢失。 优势 可以...
在PostgreSQL中,ALTER TABLE命令用于修改现有表的结构。当对表进行大规模修改时,可能会导致ALTER TABLE执行变慢的情况。 Alter Table太慢可能由以下几个因素引起:...
Users can confirm the table alteration by executing the below-provided command: \d emp_info; From the output, it is clear that the UNIQUE CONSTRAINT has been successfully applied to the selected columns. How to Remove/DROP a UNIQUE Constraint From Multiple Columns of a PostgreSQL...
How to enable PostgreSQL’s CI in your GitHub fork Postgres has a strong reputation for running on multiple different platforms. Therefore, it is important to verify that your code works across these different platforms. That’s where CI tools come in handy. PostgreSQL co...
If the constraint in Oracle is not deferrable, it will need to be dropped and re-created as deferrable, though it is sometimes possible to alter the constraint without having to drop it. Note: to avoid potential errors or bad data, place the commands for dropping and r...
Also, is there a way to convert a distributed table to not being distributed? I could then change it back to distributed and fix my colocate... without having to drop the table. The newundistribute_table()function will: return all the data of a distributed t...
Drop the inheritance parent and all the objects created on the inheritance parent.DROP TABLE .. CASCADEmight help here. These should be the same objects, except the partitioning constraints, recreated in step 6 on the partitioned table. This allows us to rename the partitioned table with the ...