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【DM版本】:dm8
【操作系统】：wind10
【CPU】:
【问题描述】*：mysql函数，dm数据库怎么写

CREATE DEFINER=`sdzg`@`%` FUNCTION `get_unique_items`(str VARCHAR(1000)) RETURNS varchar(1000) CHARSET utf8mb4 COLLATE utf8mb4_general_ci
    READS SQL DATA
BEGIN
	SET @String = str;
	SET @Occurrences = LENGTH( @String ) - LENGTH(
	REPLACE ( @String, ',', '' ));
	
	SET @ret = '';
	myloop :
	WHILE
			( @Occurrences > 0 ) DO
			
			SET @myValue = SUBSTRING_INDEX( @String, ',', 1 );
		IF
			( TRIM( @myValue ) != '' ) THEN
			IF
				(( LENGTH( @ret ) - LENGTH( REPLACE ( @ret, @myValue, '' )))= 0 ) THEN
				SELECT
					CONCAT( @ret, @myValue, ',' ) INTO @ret;
				
			END IF;
			
		END IF;
		
		SET @Occurrences = LENGTH( @String ) - LENGTH(
		REPLACE ( @String, ',', '' ));
		IF
			( @occurrences = 0 ) THEN
				LEAVE myloop;
			
		END IF;
		
		SET @String = SUBSTRING( @String, LENGTH( SUBSTRING_INDEX( @String, ',', 1 ))+ 2 );
		
	END WHILE;
	
	SET @ret = CONCAT( SUBSTRING( @ret, 1, LENGTH( @ret )- 1 ), '' );
	RETURN @ret;
    END