(1 row) UPDATE 1 postgres=# update tabs set name = 'tony' where id=5 RETURNING id || name AS idName; idname --- 5tony (1 row) postgres=# insert into tabs values(5,'tams') returning *; ERROR: duplicate key value violates unique constraint "tabs_pkey" DETAIL: Key (id)=(5) ...
[ ROW | ROWS ] ] [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY ] [ FOR { UPDATE | NO KEY UPDATE | SHARE | KEY SHARE } [ OF table_name [, ...] ] [ NOWAIT | SKIP LOCKED ] [...] ] from_item 可以是以下选项之一: [ ONLY ] table_name [ * ] [ [ AS ...
postgres=# show checkpoint_timeout;checkpoint_timeout---5min(1row)postgres=# show checkpoint_completion_target;checkpoint_completion_target---0.5(1row) max_connections 允许客户端连接的最大数目 fsync 强制把数据同步更新到磁盘,如果系统的IO压力很大,把改参数改为off 在fsync打开的情况下,优化后性能能够提...
AI代码解释 CREATE[UNIQUE]INDEX[CONCURRENTLY][[IFNOTEXISTS]name]ON[ONLY]table_name[USINGmethod]({column_name|(expression)}[COLLATEcollation][opclass[(opclass_parameter=value[,...])]][ASC|DESC][NULLS{FIRST|LAST}][,...])[INCLUDE(column_name[,...])][WITH(storage_parameter[=value][,......
postgres=# show maintenance_work_mem;maintenance_work_mem---64MB(1row) 1. 2. 3. 4. 5. 6.synchronous_commit 此参数的作用为在向客户端返回成功状态之前,强制提交等待WAL被写入磁盘。这是性能和可靠性之间的权衡。如果应用程序被设计为性能比可靠性更重要,那么关闭synchronous_commit。这意味着成功...
GET DIAGNOSTICS myresult:=ROW_COUNT;ifmyresult<>0thenreturnvalue='{"success":"执行更新'||mysql||'成功!"}';elsereturnvalue='{"success":"执行更新'||mysql||'失败!"}';endif;end; $$ language plpgsql;--实际操作createtabletest(idinteger,nametext,gen_time date,out returnvalue);insertintotest(...
CREATE TRIGGER update_timestamp_trigger BEFORE UPDATE ON your_table FOR EACH ROW EXECUTE PROCEDURE update_timestamp();效果:当插入一条新记录时,create_at 字段会自动设置为当前时间,update_at 字段保持为空或可以初始化为 NULL。当更新一条记录时,update_at 字段会自动设置为当前时间。
Update row This operation updates an existing row in a table.Delete rowOperation ID: DeleteItem This operation deletes a row from a table. Parameters 展開資料表 NameKeyRequiredTypeDescription Table name table True string Name of table Row id id True string Unique identifier of the row to ...
rownum在select列表中时重写为row_number() over ()rownum在where子句中时重写为limit... offset... 虚拟列rowid Oracle中的rowid虚拟列返回特定行的具体地址,在PostgreSQL中重写为tableoid || '#' || ctid。 字符串函数 nvl(col, value) Oracle中的nvl(col, value)用来设置默认值,col为空就设置为value;在...
[ ROW | ROWS ] ] [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY ] [ FOR { UPDATE | NO KEY UPDATE | SHARE | KEY SHARE } [ OF table_name [, ...] ] [ NOWAIT | SKIP LOCKED ] [...] ] where from_item can be one of: [ ONLY ] table_name [ * ] [ [ ...