IF EXISTS (SELECT 1 FROM SYSOBJECTS WHERE name = 'tba')
BEGIN
    DROP TABLE tba
END
GO
CREATE TABLE tba
(
    col1 VARCHAR(18)
)
GO
INSERT INTO tba
SELECT '210603198502121018' UNION
SELECT '210603850212101'


SELECT * FROM tba
WHERE CONVERT(VARCHAR(8),'1947-07-01',112) <= CASE LEN(col1) WHEN 18 THEN SUBSTRING(col1,7,8)
                                                             WHEN 15 THEN CONVERT(VARCHAR(8),CAST(SUBSTRING(col1,7,6) AS DATETIME),112) END 
      AND CONVERT(VARCHAR(8),'1987-6-30',112) >= CASE LEN(col1) WHEN 18 THEN SUBSTRING(col1,7,8)
                                                                WHEN 15 THEN CONVERT(VARCHAR(8),CAST(SUBSTRING(col1,7,6) AS DATETIME),112) END

------解决方案--------------------
SQL code

create table fe(身份证号 varchar(18))

insert into fe
select '372524198203033778' union all
select '370206195609141619' union all
select '370221193501010048' union all
select '370221194801010048' union all
select '370221490102004'


select *
from fe
where cast(case len(身份证号) 
           when 18 then substring(身份证号,7,8)
           when 15 then '19'+substring(身份证号,7,6) end as date)
between '1947-07-01' and '1952-06-30'

/*
身份证号
------------------
370221194801010048
370221490102004

(2 row(s) affected)
*/

------解决方案--------------------
SQL code
select case length(id_card) when 15 then cast('19'+substring(ID_card,7,2)+'-'+substring(ID_card,11,2)+'-'+substring(ID_card,13,2) as datetime)
                            when 18 then cast(substring(ID_card,7,4)+'-'+substring(ID_card,11,2)+'-'+substring(ID_card,13,2) as datetime) 
AS birthdate 
where birthdate between '1947-7-1' and '1952-6-30'