SQL SERVER 查找某个字符在字符串中出现的次数

　　首先需要建立一个数字辅助表dbo.nums,使用nums表将字符串扩充为字符串长度行，然后对每一行进行字符串截取, 最后统计字符出现的次数.

View Code

-- Generating Nums Table
-- 来源：SQL SERVER 2005 技术内幕
SET NOCOUNT ON;
USE tempdb;
GO

IF OBJECT_ID('dbo.Nums') IS NOT NULL
DROP TABLE dbo.Nums;
GO
CREATE TABLE dbo.Nums(n INT NOT NULL PRIMARY KEY);
DECLARE @max AS INT, @rc AS INT;
SET @max = 1000000;
SET @rc = 1;

INSERT INTO Nums VALUES(1);
WHILE @rc * 2 <= @max
BEGIN
INSERT INTO dbo.Nums SELECT n + @rc FROM dbo.Nums;
SET @rc = @rc * 2;
END

INSERT INTO dbo.Nums
SELECT n + @rc FROM dbo.Nums WHERE n + @rc <= @max;
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: xx
-- Create date: 2011年7月15日21:07:32
-- Description: 查找字符串中某个字符出现的次数
-- 思路：使用nums表将字符串扩充为字符串长度行，然后对每一行进行字符串截取，
-- 最后统计字符出现的次数
-- =============================================
CREATE FUNCTION [dbo].[fnQueryCharCountFromString]
(
@Str NVARCHAR(MAX), --待查找字符串
@Spilt CHAR(1) --需查找的字符
)
RETURNS INT
AS
BEGIN

DECLARE @Count INT
SELECT @Count = COUNT(*)
FROM (
SELECT SUBSTRING(s,n,1) AS split
FROM (
SELECT @Str AS s,n
FROM dbo.nums
WHERE n < LEN(@Str)) D
) A
WHERE A.split = @Spilt

RETURN @Count;

END

如果需要查找某n个字符出现的次数,在SUBSTRING中截取的长度取n即可。