SELECT*FROMpg_enum; 4.8 Sakila中的用户定义函数User-defined functions in Sakila 如果您真正经营一家DVD租赁商店,则可能需要反复回答许多问题,例如特定商店中的电影是否有存货或特定客户的余额。在这些情况下,用户定义的函数将非常有用。Sakila数据库有几个预定义的用户定义函数,它们可以像内置函数一样在查询中使用。
第一:查询语言PostQUEL被SQL(在服务器中实现)所取代。(接口库libpq是以PostQUEL命名的。)直到PostgreSQL才支持子查询,但在Postgres95中可以通过用户定义的SQL函数来模仿子查询。重新实现了聚合函数。还添加了对GROUP BY查询子句的支持。 第二:提供了一个用于交互式SQL查询的新程序(psql),它使用GNU Readline。这在很...
Adding new extension lt_sm to support sm2, sm3 and sm4 encryption. lt_sm is a extension for LightDB that provides a series of functions for sm2, sm3 and sm4 encryption algorithms. Data can be encrypted and decrypted using the above functions. Seelt_smfor more details. Adding New GUC par...
Custom data types : user defined types Hands on examples for composite types, enumerated types, and range types. Summaries with Aggregate Filters and Windows Aggregate filtering with window functions to strip out just the information you want Using FILTER vs CTEs and CASE WHEN When aggregating bas...
Previously you had to decide on these table properties up front, and then you went with your decision. Or if you really wanted to change your decision, you needed to start over. The good news is thatin Citus 10, we introduced 2 new user-defined functions (...
Understanding PostgreSQL User-Defined FunctionsStructured vs. Semi-Structured vs. Unstructured Data in PostgreSQLUnderstanding SQL Aggregate FunctionsUnderstanding Foreign Keys in PostgreSQLUnderstanding FILTER in PostgreSQL (With Examples)Understanding PostgreSQL FunctionsUnderstanding PostgreSQL WITHIN GROUPUnderstanding...
一、脚本说明 1.环境 docker部署的postgres服务端,宿主机安装postgres客户端,使用命令进行备份恢复 2.数据库备份: 使用 pg_dump 命令来备份数据库,并将其压缩为 .sql.gz 或者.tar.gz 格式。 在备份时会包含创建数据库的语句。 3.备份清理: 使用 fin
Adding new extension lt_sm to support sm2, sm3 and sm4 encryption. lt_sm is a extension for LightDB that provides a series of functions for sm2, sm3 and sm4 encryption algorithms. Data can be encrypted and decrypted using the above functions. Seelt_sm for more details. ...
*/ #define HASH_STRINGS 0x0010 /* Select support functions for string keys */ #define HASH_BLOBS 0x0020 /* Select support functions for binary keys */ #define HASH_FUNCTION 0x0040 /* Set user defined hash function */ #define HASH_COMPARE 0x0080 /* Set user defined comparison function *...
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. ...