DROP TABLE IF EXISTS your_table_name; 如果表存在,则将其删除;如果表不存在,则不执行任何操作。 使用PL/pgSQL函数:可以编写一个PL/pgSQL函数来检查表是否存在,并在需要时抛出自定义错误。 代码语言:sql 复制 CREATE OR REPLACE FUNCTION check_table_exists(table_name text) RETURNS boolean AS $...
You have a table address and want to check if there’s already a row with address_id = 100 existing. You can use COUNT to check: SELECT COUNT(*) FROM address WHERE address_id = 100; But if you are looking for a faster query with a yes/no answer: SELECT EXISTS(SELECT 1 FROM ...
>>> create table if not exists people(name text,age int(2),gender char(1)); 如上代码表示...
test=#ALTERTABLEproductsDROPCONSTRAINTproducts_name_uk;ALTERTABLEtest=# \d products;Table"hr.products"Column|Type|Collation|Nullable|Default---+---+---+---+---product_no|integer||notnull|name|text||notnull|price|numeric|||Indexes: "products_pkey"PRIMARYKEY, btree (product_no)Checkconstraints...
table_constraint 可以是以下选项之一:[ CONSTRAINT constraint_name ] { UNIQUE ( column_name [, ... ] ) [ USING INDEX TABLESPACE tablespace ] | PRIMARY KEY ( column_name [, ... ] ) [ USING INDEX TABLESPACE tablespace ] | CHECK ( expression ) | FOREIGN KEY ( column_name [, ... ] ...
the CREATE TABLE IF NOT EXISTS command will simply not create a new table, and PostgreSQL will not throw an error. However, it’s important to note that it will not check for the structure of an existing table—if a table with the same name but different columns exists, it won’t atte...
--exclude-table-data=PATTERN do NOT dump data for the specified table(s) --if-exists 当删除对象时使用IF EXISTS --inserts 以INSERT命令,而不是COPY命令的形式转储数据,使用该选项可以把数据加载到非pg数据库,会使恢复非常慢 该选项为每行生成1个单独的insert命令,?在恢复过程中遇到错误,将会丢失1行而...
例:create table postgtest (id serial primary key,title varchar(255) not null, content text check(length(content) > 3),is_draft boolean default true , create_date timestamp default 'now'); 插入 INSERT INTO TABLE_NAME (column1, column2, column3,...columnN)VALUES (value1, value2, value...
#default_statistics_target = 100 # 为没有通过ALTER TABLE SET STATISTICS设置列相关目标的表列设置默认统计目标。 range 1-10000 # 默认值是 100 #constraint_exclusion = partition # constraint_exclusion的允许值是on(对所有表检查约束)、off(从不检查约束)和partition(只对继承的子表和UNION ALL子查询检查约...
INSERT ON CONFLICT DO UPDATE:If record matched, it is updated with the new data value. INSERT ON CONFLICT DO NOTHING:If record matched, it skips the record or error. Below is a full demonstration of this: Create a table with sample data: ...