有2个表，A（列a）和B（列b）。我想找到表B列b中表A列a中每个值的出现次数

Question

有2个表格，A（列＆＃39; a＆＃39;）和B（列＆＃39; b＆＃39;）。我想在表A列中找到每个值的出现次数＆＃39; a＆＃39;在表B栏中＆＃39; b＆＃39;。

目前，我正在使用蛮力方法，而且速度太慢了。有什么可能是解决这个问题的更好方法？

示例：

输出

蛮力方法：

WHILE(SELECT COUNT(*) FROM A) > 0
BEGIN
    DECLARE @Val VARCHAR(100);
    DECLARE @ValSpaceMod VARCHAR(100);
    DECLARE @ModSpaceValSpaceMod VARCHAR(100);
    DECLARE @ModSpaceVal VARCHAR(100);
    DECLARE @cnt integer;

    SELECT TOP 1 @Val = a FROM A

    SET @ValSpaceMod = @Val + ' %';
    SET @ModSpaceVal = '% ' + @Val;
    SET @ModSpaceValSpaceMod = '% ' + @Val + ' %';

    SELECT @cnt = COUNT(*) FROM B 
    WHERE ( LOWER(B.b) LIKE lower(@Val) 
       OR   LOWER(B.b) LIKE lower(@ValSpaceMod)
       OR   LOWER(B.b) LIKE LOWER(@ModSpaceValSpaceMod)
       OR   LOWER(B.b) LIKE LOWER(@ModSpaceVal)
          )

    PRINT @Val + ' ' + CAST(@cnt AS VARCHAR)

    DELETE A WHERE a= @Val
END

Answer 1

这是一种可能的解决方案。结果并不完全等于您的预期输出，但这是因为我认为表B上的第四行应该增加A计数。如果这不对，请告诉我，以便我可以调整脚本。

if object_id ('tempdb..#tbT1') is not null
drop table #tbT1
GO

if object_id ('tempdb..#tbT2') is not null
drop table #tbT2
GO

create table #tbT1 (
    v char(1) collate SQL_Latin1_General_CP1_CI_AS
)

create table #tbT2 (
    t varchar(255) collate SQL_Latin1_General_CP1_CI_AS
)

insert into #tbT1
values ('A'), ('B'), ('C'), ('D')

insert into #tbT2
values ('A first value B second value'),
    ('B second value D fourth value'),
    ('D fourth value'),
    ('C third value Afirst')


select t1.v, sum (
    len(t2.t) - len(replace(t2.t, ' ' + t1.v + ' ', '  ')) -- middle occurrences
  + case when t2.t like t1.v + ' %' then 1 else 0 end -- add starting occurence
  + case when t2.t like '% ' + t1.v then 1 else 0 end -- add ending occurence
  ) as nOccurencies
from #tbT1 t1, #tbT2 t2
group by t1.v

Answer 2

请尝试以下查询（使用关键字like获取表A列中的每个值的出现次数＆＃39; a＆＃39;在表B列中＆＃39; b＆＃39; ）

SELECT  [A].a AS SearchTerm
        ,(  SELECT  count(*)
            FROM    [B]
            WHERE   b LIKE '%'+[A].a+' %'
            COLLATE Latin1_General_CS_AS )  AS  Occurrences
FROM    [A]