·IsNull(check_expression,replacement_value)对check_expression进行检测,如果值为空,函数将返回replacement_value。如果 check_expression值非空,该函数将返回check_expression。 --- select AVG(Rent) AVG(ISNULL(Rent,0)) from Inventory --- ·Coalesce(expression[,...n])函数经常用于合并被拆分到若干列中的...
{ "null_value_no_indicator_parameter", ERRCODE_NULL_VALUE_NO_INDICATOR_PARAMETER }, { "numeric_value_out_of_range", ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE }, { "sequence_generator_limit_exceeded", ERRCODE_SEQUENCE_GENERATOR_LIMIT_EXCEEDED }, { "string_data_length_mismatch", ERRCODE_STRING_DATA...
30. isnull(expression,replacement_value) :使用指定的替换值替换 NULL。ISNULL(price, $10.00); 等价于:Case WHEN Expression1 is NULL Then Expression2 ELSE Expression1。 31. isdate(expression) :确定输入表达式是否为有效的日期如果输入表达式是有效的日期,那么 ISDATE 返回 1;否则,返回 0 32. isnumeric...
application_name is '应用名(客户端名)'; drop foreign table if exists pg_log_tue; create foreign table pg_log_tue( log_time timestamp ,user_name text ,database_name text ,process_id integer ,connection_from text ,session_id text ,session_line_num bigint ,command_tag text ,session_...
mydb=# ALTER TYPE mood ADD VALUE IF NOT EXISTS 'happier' AFTER 'happy'; mydb=# \dT+ mood; List of data types Schema | Name | Internal name | Size | Elements | Owner | Access privileges | Description ---+---+---+---+---+---+---+--- public | mood | mood | 4 | sad...
self.dcs.initialize(create_new=(self.cluster.initialize is None), sysid=self.state_handler.sysid) if not (self.cluster.is_unlocked() or self.cluster.config and self.cluster.config.data) and self.has_lock(): self.dcs.set_config_value(json.dumps(self.patroni.config.dynamic_configuration, sep...
Is Null –check if a value is null or not. Section 3. Joining Multiple Tables Joins –show you a brief overview of joins in PostgreSQL. Table aliases –describes how to use table aliases in the query. Inner Join–select rows from one table that have the corresponding rows in other tables...
# name = value # ("="是可选的.)可以使用空格.注释是在一行的任何地方用"#"开头.参数名和允许值的完整列表可以在PostgreSQL文档中找到. # 该文件中显示的注释化设置表示默认值.重新注释设置不足以将其还原为默认值;您需要重新加载服务器. # # 此文件在服务器启动时以及服务器接收到SIGHUP信号时读取.如果...
TO ( { partition_bound_expr | MINVALUE | MAXVALUE } [, ...] ) | WITH ( MODULUS numeric_literal, REMAINDER numeric_literal ) 父表与分区解除绑定关系: ALTERTABLE[ IFEXISTS] name DETACHPARTITIONpartition_name; 删除分区及其中数据(与删除表方法相同) ...
Index Cond: (price = '100'::numeric) (7 rows) 将LIMIT/OFFSET 子句去掉,SQL 变为: EXPLAIN SELECT FROM orders WHERE price = 100 ORDER BY order_id; 执行计划变为: QUERY PLAN --- Sort (cost=2638.03..2640.53 rows=997 width=4) Sort Key: order_id -> Bitmap Heap Scan on orders (cost...