WITH 语句可以包含多个表达式,每个表达式之间使用逗号分隔,例如: WITH cte1 AS ( SELECT * FROM table1 ), cte2 AS ( SELECT * FROM table2 ) SELECT * FROM cte1 JOIN cte2 ON cte1.id = cte2.id; 复制代码 在实际使用中,WITH 语句可以用于创建递归查询、多层嵌套查询、子查询共享等复杂查询场景。 0...
2.nullif(exper1,exper2)如果expr1= expr2 成立,那么返回值为NULL,否则返回值为 expr1 十、 WITH AS 和 OVER (ORDER BY ) 转 mssql: WITH questions AS ( SELECT tx.ID,tx.QID, ROW_NUMBER() OVER (ORDER BY tx.ID) AS RowNumber FROM QuestionTX tx ) SELECT * FROM questions ; 1. 2. 3....
WITHtotal_tAS(--临时表:获取9月份数量总数量为:6条SELECTCOUNT(TYPE)AStcFROMbiz_ticket TWHERE--当前时间T .create_time>='2019-09-01 00:00:00'ANDT .create_time<='2019-09-30 23:59:59'), type_zbc_tAS(--临时表:获取9月份type='REQ'的数量为:2条SELECTCOUNT(TYPE)ASzbcFROMbiz_ticket TWHER...
WITH RECURSIVE r AS (SELECT * FROM test1 as t WHERE m_id = 18union ALLSELECT t.* FROM ***.merchant as t, r WHERE ***.par = r.m_id ) SELECT * FROM r where stat = 1 ORDER BY m_id它会一直递归调用,直到没有记录返回。第一步,会得到 SELECT * FROM test1 as t WHERE m_id =...
1、COALESCE用法: COALESCE (expression_1, expression_2, ...,expression_n)依次参考各参数表达式,遇到非[null]值即停止并返回该值。如果所有的表达式都是空值,最终将返回一个空值。使用COALESCE在于大部分包含空值的表达式最终将返回空值。 2、::的作用==》 转换类型 a.dc::date + INTERVAL '1 DAY 7:20:00...
PostgreSQL 官方文档用求序列和的例子,演示了 WITH RECURSIVE 的用法: postgres=#WITHRECURSIVE t(n)AS( VALUES(1) UNIONALL SELECTn+1FROMtWHEREn<100 ) SELECTsum(n)FROMt; sum --- 5050 (1row) 公交换乘问题 实际的,工业强度的换乘算法肯定会更多地利用地理相关的信息做剪枝操作。这里给出的例子仅仅为了...
下面咱们说下PostgreSql中generate_series函数的用法: 用处:他可以按照不同的规则来生成填充数据 语法: 也可以用递归来做,其中recursive函数配合with查询来实现遍历,效率会更高一些: 1 with recursive t(n) as ( 2 select date('2020-10-27') 3 union all 4 select n+1from t where n < date('2020-11-...
WITHRECURSIVE-- in_usa 包含所有的美国境内的位置 IDin_usa(vertex_id)AS(SELECTvertex_idFROMverticesWHEREproperties->>'name'='United States'UNIONSELECTedges.tail_vertexFROMedgesJOINin_usaONedges.head_vertex=in_usa.vertex_idWHEREedges.label='within'),-- in_europe 包含所有的欧洲境内的位置 IDin_eu...
WITH subquery AS (SELECT column2 FROM table2 WHERE condition) UPDATE table1 SET column1 = subquery.column2 WHERE condition; ``` 4.使用CASE语句更新数据: 在UPDATE语句中使用CASE语句可以根据条件更新不同的值。例如,根据特定条件更新不同的列: ```sql UPDATE table1 SET column1 = CASE WHEN condition...
to fail. This only appears to happen with the pgsql plugin when both sql_use_copy is true and as_path is part of the aggregate. relevant parts of my nfacctd.conf: aggregate[bgp_hourly]: src_as, dst_as, peer_src_ip, peer_dst_ip, ...