postgresql truncate if exists

In-depth interpretation of sequences in PostgreSQL and their related functions, and interpretation of postgresql I. Introduction A sequence object (also called a SEQUENCE generator) is a special single-row table created using create sequence. A

This article mainly introduces how to migrate the database used by Django from MySQL to PostgreSQL. It also mentions some precautions, if you want to migrate the database from mysql to PostgreSQL, you can see that we have already migrated the

First, restore disk space: In PostgreSQL, data rows that are deleted or updated using the Delete and UPDATE statements are not actually deleted, but only the state of the row is deleted or expired on the physical address of the old version of the

PostgreSQL tutorial (II): Schema description, postgresqlschema A database contains one or more naming modes. The schema also contains tables. The schema also contains other named objects, including data types, functions, and operators. The same

A database contains one or more naming modes. The schema also contains tables. The schema also contains other named objects, including data types, functions, and operators. The same object name can be used in different modes without causing

Original: http://www.cnblogs.com/stephen-liu74/archive/2012/04/25/2291526.htmlA database contains one or more named patterns, and the schema contains the tables. The schema also contains other named objects, including data types, functions, and

A database contains one or more named schemas, and the schema contains tables. The pattern also contains other named objects, including data types, functions, and operators. The same object name can be used in a different pattern without causing a

Java SQL statement optimization experience and PostgreSQL statement Optimization Java SQL statement optimization experience (1) select the most efficient table name sequence (only valid in the rule-based seo/'target = '_ blank'> Optimizer ):The

Comparison of not in, JOIN, is null, not exists EfficiencyStatement 1: select count (*) from A where A. a not in (select a from B)Statement 2: select count (*) from A left join B on A. a = B. a where B. a is nullStatement 3: select count (*) from A

Comparison of not in, JOIN, is null, not exists Efficiency Statement 1: select count (*) from A where A. a not in (select a from B) Statement 2: select count (*) from A left join B on A. a = B. a where B. a is null Statement 3: select count (*)