Splitting a String into rows

问题

I have a table with a field consisting of multiple strings seperated by a '+'.

Each part of the string has a length of either 2 or 3 chars. Example: 'ab+cde+fg'.

Each row has 1 to 3 parts (so some rows don't need spliting). The above example should return 3 rows: 'ab', 'cd' and 'fg'.

I have searched the internet for stored procedures, but none seem to work for my particular needs. I don't have the SQL-skills myself to write such procedure.

回答1:

The general algorithm works like this:

DECLARE input CHAR(100);
DECLARE separator_position INTEGER;

SET input = 'AA+CCC+D';

CREATE TABLE
   #output
(
   part CHAR(10)
);

SET separator_position = POSITION('+' IN input);

WHILE separator_position > 0 DO

  INSERT INTO #output (part) VALUES (SUBSTRING(input, 1, separator_position - 1));
  SET input = SUBSTRING(input, separator_position + 1, 100); 

  SET separator_position = POSITION('+' IN input);
END WHILE;

INSERT INTO #output(part) VALUES (SUBSTRING(input, 1, 10));

SELECT * FROM #output;

This code will insert 3 rows AA, CCC, D into the temporary table #output.

Here is a version that works with multi character delimiters and also contains a part counter:

DECLARE @input STRING;
DECLARE @delimiter_position INTEGER;
DECLARE @delimiter STRING;

TRY DROP TABLE #output; CATCH ALL END TRY;

SET @delimiter = CHAR(13) + CHAR(10);
SET @input = 'AA' + CHAR(13) + CHAR(10) + 'CCC' + CHAR(13) + CHAR(10) + 'D';

CREATE TABLE
   #output
(
     counter AUTOINC
   , part CHAR(10)
);

SET @delimiter_position = POSITION(@delimiter IN @input);

WHILE @delimiter_position > 0 DO

  INSERT INTO #output (part) VALUES (LEFT(@input, @delimiter_position - 1));
  SET @input = RIGHT(@input, LENGTH(@input) - (@delimiter_position + LENGTH(@delimiter)) + 1); 

  SET @delimiter_position = POSITION(@delimiter IN @input);
END WHILE;

INSERT INTO #output(part) VALUES (LEFT(@input, LENGTH(@input)));

SELECT * FROM #output;

来源：https://stackoverflow.com/questions/5352547/splitting-a-string-into-rows