postgres=#createtabletbl(idintprimarykey,infotext);CREATETABLEpostgres=#createtabletbl1(idintreferencestbl(id), infotext);CREATETABLEpostgres=# \d tblTable"public.tbl"Column|Type|Modifiers---+---+---id|integer|notnullinfo|text|Indexes: "tbl_pkey"PRIMARYKEY, btree (id) Referencedby:TABLE"tbl...
RENAME [ COLUMN ] column TO new_column ALTER TABLE name RENAME TO new_name 其中action 可以是以选项之一: ADD [ COLUMN ] column_type [ column_constraint [ ... ] ] DROP [ COLUMN ] column [ RESTRICT | CASCADE ] ALTER [ COLUMN ] column TYPE type [ USING expression ] ALTER [ COLUMN ]...
postgres=# create table tbl(id int primary key,info text);CREATE TABLEpostgres=# create table tbl1(id int references tbl(id), info text);CREATE TABLEpostgres=# \d tblTable "public.tbl"Column | Type | Modifiers---+---+---id | integer | not nullinfo | text |Indexes:"tbl_pkey" PR...
ALTER TABLE [ ONLY ] name [ * ] action [, ... ] ALTER TABLE [ ONLY ] name [ * ] RENAME [ COLUMN ] column TO new_column ALTER TABLE name RENAME TO new_name其中action 可以是以选项之一:ADD [ COLUMN ] column_type [ column_constraint [ ... ] ] DROP [ COLUMN ] column [ ...
{ "fdw_column_name_not_found", ERRCODE_FDW_COLUMN_NAME_NOT_FOUND }, { "fdw_dynamic_parameter_value_needed", ERRCODE_FDW_DYNAMIC_PARAMETER_VALUE_NEEDED }, { "fdw_function_sequence_error", ERRCODE_FDW_FUNCTION_SEQUENCE_ERROR }, { "fdw_inconsistent_descriptor_information", ERRCODE_FDW_...
create table toast_t(id int,vname varchar(48),remark text); --其中remak数据类型是text,列值长度超过2KB则就会自动产生toast表来存储。 更改表的存储方式为Toast 语法: ALTER TABLE toast_t ALTER COLUMN vname SET STORAGE {PLAIN | EXTENDED | MAIN | EXTERNAL}; ...
用户通常只需要设置参数vacuum_cost_delay和vacuum_cost_limit,其它的参数使用默认值即可。VACUUM 和ANALYZE命令在执行过程中,系统会计算它们执行消耗的资源,资源的数量用一个正整数表示,如果资源的数量超过vacuum_cost_limit,则执行命令的进程会进入睡眠状态,睡眠的时间长度是是vacuum_cost_delay。vacuum_cost_limit的值...
[NULLS{FIRST|LAST}][,...]][LIMIT{count|ALL}][OFFSETstart[ROW|ROWS]][FETCH{FIRST|NEXT}[count]{ROW|ROWS}ONLY][FOR{UPDATE|NOKEYUPDATE|SHARE|KEYSHARE}[OFtable_name[,...]][NOWAIT|SKIPLOCKED][...]]#from_item 可以是以下选项之一[ONLY]table_name[*][[AS]alias[(column_alias[,...])]...
CREATE TABLE table_name ( ... ) [ PARTITION BY { RANGE | LIST } ( { column_name | ( expression ) } 1. 2. 2、创建分区(子表) CREATE TABLE table_name PARTITION OF parent_table [ ( ) ] FOR VALUES partition_bound_spec 1.
substr(column_name,start,len)截取colunm_name列,从start开始len个字符。 例:substr('sequence',3,2)截取sequence列,从第3个字符开始,到其后面2个字符(第4个字符)之间的字符串。 3.13group by()和order by()(分组和排序) group by name1根据name1进行分组; ...