Работа с датами в MS SQL

 CREATE FUNCTION CheckDates(@inputString NVARCHAR(MAX)) 
RETURNS BIT 
AS 
BEGIN 
    DECLARE @dateRegex NVARCHAR(MAX) = '[0-9]{1,2}[./-][0-9]{1,2}[./-][0-9]{4}' 
    DECLARE @dateCount INT = (SELECT COUNT(*) FROM STRING_SPLIT(@inputString, ' ') WHERE TRY_CONVERT(DATETIME, value) IS NOT NULL) 
    DECLARE @datePairs TABLE (date1 DATETIME, date2 DATETIME) 
    DECLARE @result BIT = 1 
 
    -- Проверяем, что количество дат больше или равно 4 
    IF @dateCount < 4 
        SET @result = 0 
    ELSE 
    BEGIN 
        -- Извлекаем даты из строки 
        INSERT INTO @datePairs 
        SELECT d1.date AS date1, d2.date AS date2 
        FROM (SELECT value AS date FROM STRING_SPLIT(@inputString, ' ') WHERE TRY_CONVERT(DATETIME, value) IS NOT NULL) d1 
        CROSS JOIN (SELECT value AS date FROM STRING_SPLIT(@inputString, ' ') WHERE TRY_CONVERT(DATETIME, value) IS NOT NULL) d2 
        WHERE d1.date < d2.date 
 
        -- Проверяем, что разность между всевозможными парами дат не превышает 21 день 
        IF EXISTS (SELECT 1 FROM @datePairs WHERE DATEDIFF(DAY, date1, date2) > 21) 
            SET @result = 0 
    END 
 
    RETURN @result 
END 
 

 CREATE FUNCTION CheckDates(@inputString VARCHAR(MAX)) 
RETURNS INT 
AS 
BEGIN 
    DECLARE @dateList TABLE (dateValue DATE) 
 
    DECLARE @pos INT 
    DECLARE @len INT 
    DECLARE @dateString VARCHAR(MAX) 
    DECLARE @dateValue DATE 
 
    SET @pos = 1 
    WHILE @pos <= LEN(@inputString) 
    BEGIN 
        SET @len = CHARINDEX('.', @inputString, @pos) - @pos 
        IF @len < 0 
            SET @len = LEN(@inputString) - @pos + 1 
 
        SET @dateString = SUBSTRING(@inputString, @pos, @len) 
 
        BEGIN TRY 
            SET @dateValue = CAST(@dateString AS DATE) 
            INSERT INTO @dateList (dateValue) VALUES (@dateValue) 
        END TRY 
        BEGIN CATCH 
            -- do nothing 
        END CATCH 
 
        SET @pos = @pos + @len + 1 
    END 
 
    DECLARE @dateCount INT 
    SET @dateCount = (SELECT COUNT(*) FROM @dateList) 
 
    IF @dateCount < 4 
        RETURN 0 
 
    DECLARE @validPairs TABLE (date1 DATE, date2 DATE) 
    INSERT INTO @validPairs (date1, date2) 
    SELECT d1.dateValue, d2.dateValue 
    FROM @dateList d1, @dateList d2 
    WHERE d1.dateValue < d2.dateValue 
    AND DATEDIFF(DAY, d1.dateValue, d2.dateValue) <= 21 
 
    IF (SELECT COUNT(*) FROM @validPairs) = (SELECT COUNT(*) FROM @dateList) * (SELECT COUNT(*) FROM @dateList) / 2 
        RETURN 1 
    ELSE 
        RETURN 0 
END 

 SELECT dbo.CheckDates('1.1.2022djdi1.1.2022deqi1.1.2022jdidjei1.1.2022')