test=#altertabletbl_primaryaddconstraintpk_tbl_primary_a_bprimarykey(a,b);ALTERTABLE 方式二 将重复数据全部删除 第一步:删除主键约束,清空表,写入测试数据 altertabletbl_primarydropconstraintpk_tbl_primary_a_b ;ALTERTABLEtest=#deletefromtbl_primary;DELETE8test=#insertintotbl_primary (a,b)values(1,...
1.在字段后加primary key 约束 id varchar(32) primary key 2.在表创建好之后添加外键约束 alter table student add constraints pk_student_id PRIMARY key(id); 3.在创建表的语句的最后面使用 constraints pk_表名_字段名 primary key(字段名) 4.删除主键约束alter table student drop constraints pk_student...
Summary: in this tutorial, you will learn about the PostgreSQL primary key and how to manage primary key constraints effectively. Introduction to PostgreSQL primary key A primary key is a column or a group of columns used to uniquely identify a row in a table. The column that participates in...
casewhenconstraint_type='PRIMARY KEY'then'PRI' whenconstraint_type='UNIQUE'then'UNI' else'' end FROMinformation_schema.table_constraints tc JOINinformation_schema.constraint_column_usageASccuUSING(constraint_schema, constraint_name) JOINinformation_schema.columnsAScONc.table_schema=tc.constraint_schemaAND...
PostgreSQL 创建表格 PostgreSQL 使用 CREATE TABLE 语句来创建数据库表格。 语法 CREATE TABLE 语法格式如下: CREATE TABLE table_name( column1 datatype, column2 datatype, column3 datatype, ... columnN datatype, PRIMARY KEY( ..
create table "SysUser"( "UserId" serial primary key, "UserName" varchar(50), "Pwd" varchar(50) ); --说明:只能设置一列作为主键,主键默认名称为tablename_pkey。 1. 2. 3. 4. 5. 6. 2.使用表级约束设置主键 create table "SysUser"( ...
i.indrelid = 'your_table_name'::regclass; your_table_name需要替换为你要操作的数据表名。 2、删除主键 确认主键信息后,可以使用以下SQL语句删除主键: ALTER TABLE your_table_name DROP CONSTRAINT your_primary_key_name; your_table_name为数据表名,your_primary_key_name为主键约束名。
CREATETABLEpublic.tb_test_alarm(idvarchar(64)NOTNULL,alarm_typevarchar(10)NOTNULL,happen_time timestamptzNOTNULL,create_time timestamptzNULL,update_time timestamptzNULL,"desc"textNULL,device_idvarchar(64)NOTNULL,CONSTRAINTtb_test_pkPRIMARYKEY(id)); ...
DROP PRIMARY KEY (删除主键),语法如下: ALTER TABLE table_name DROP CONSTRAINTMyPrimaryKey; 如果是 MYSQL ,代码是这样: ALTER TABLE table_name DROP PRIMARY KEY; 实例 创建COMPANY 表(下载 COMPANY SQL 文件),数据内容如下: runoobdb# select * from COMPANY;id|name|age|address|salary---+---+---...
companyTable"public.company"Column|Type|Collation|Nullable|Default---+---+---+---+---id|integer||notnull|name|text||notnull|age|integer||notnull|address|character(50)|||salary|real|||Indexes:"company_pkey"PRIMARY KEY,btree(id)"salary_index"btree(salary) 你可以使用\di命令列出数据库中所...