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| DELIMITER $$
CREATE FUNCTION distance_inference_basique( src VARCHAR(255), cible VARCHAR(255) )
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE COUNT1, COUNT2 INT;
DECLARE I, J, L INT;
DECLARE C CHAR(1);
## CAS ELEMENTAIRES
IF SOURCE IS NULL or CIBLE IS NULL
THEN RETURN NULL;
END IF;
IF SOURCE = CIBLE THEN
RETURN 0;
END IF;
## LES AUTRES CAS, MAINTENANT !
SET COUNT1 = 0;
SET COUNT2 = 0;
SET I = 1;
SET J = 1;
SET L = CHAR_LENGTH(SOURCE);
premiere_passe:WHILE I <= L DO
SET C = SUBSTRING(SOURCE, I, 1);
IF LOCATE(C, CIBLE, J) > 0 THEN
SET COUNT1 = COUNT1 + 1 ;
SET J = LOCATE(C, CIBLE, J) + 1 ;
END IF;
SET I = I + 1;
END WHILE;
IF COUNT1 = 0 THEN RETURN 0; END IF;
SET I = 1;
SET J = 1;
SET L = CHAR_LENGTH(CIBLE);
seconde_passe:WHILE I <= L DO
SET C = SUBSTRING(CIBLE, I, 1);
IF LOCATE(C, SOURCE, J) > 0 THEN
SET COUNT2 = COUNT2 + 1;
SET J = LOCATE(C, SOURCE, J) + 1;
END IF;
SET I = I + 1;
END WHILE;
IF COUNT1 < COUNT2 THEN
SET COUNT1 = COUNT2;
END IF;
RETURN COUNT1;
END $$ |
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