Credit debit
In this example you are shown how to split a single column into two separate columns and also below you are
told how to combine two tables into a single table. Here we are splitting cash amounts into credit and debit.
Table 1 shows the results without the split column and Table 2 shows what we get when the column is split into two.
| whn | description | amount |
|---|---|---|
| 2006-11-01 | Wages | 50 |
| 2006-11-02 | Company Store | -10 |
| 2006-11-03 | Company Store | -10 |
| 2006-11-04 | Company Store | -10 |
| 2006-11-05 | Company Store | -10 |
| 2006-11-06 | Company Store | -10 |
| whn | description | cshIN | cshOUT |
|---|---|---|---|
| 2006-11-01 | Wages | 50 | |
| 2006-11-02 | Company Store | 10 | |
| 2006-11-03 | Company Store | 10 | |
| 2006-11-04 | Company Store | 10 | |
| 2006-11-05 | Company Store | 10 | |
| 2006-11-06 | Company Store | 10 |
DROP TABLE transact
CREATE TABLE transact(
whn DATE,
description VARCHAR(20),
amount INTEGER );
INSERT INTO transact VALUES ('2006-11-01','Wages',50);
INSERT INTO transact VALUES ('2006-11-02','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-03','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-04','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-05','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-06','Company Store',-10);
To split a column into two you have to use a CASE function as shown in the example.
The SUBSTRING used in the example is used to get rid of the negative sign infront of the number
so that there are only positive numbers in the table.
To combine two columns into a single one you also use a CASE function to do this with this example you can use this code:
SELECT w AS dte, d AS description,
CASE WHEN (a>=0)
THEN a ELSE NULL END AS amount,
CASE WHEN (b>=0)
THEN b ELSE NULL END AS amount
FROM
(SELECT x.whn AS w, x.description AS d,
x.cshIN AS a, x.cshOUT AS b
FROM transact x
JOIN transact y ON (x.whn>=y.whn)
GROUP BY x.whn, x.description, x.amount) t
SELECT w AS dte, d AS description,
CASE WHEN (a>=0) THEN a ELSE NULL END AS cshIN,
CASE WHEN (a<0) THEN SUBSTRING(a,2,10) ELSE NULL END AS cshOUT
FROM
(SELECT x.whn AS w, x.description AS d,
x.amount AS a
FROM transact x
JOIN transact y ON (x.whn>=y.whn)
GROUP BY x.whn, x.description, x.amount) t
SELECT w AS dte, d AS description,
CASE WHEN (a>=0) THEN a ELSE NULL END AS cshIN,
CASE WHEN (a<0) THEN SUBSTR(a,2,10) ELSE NULL END AS cshOUT
FROM
(SELECT x.whn AS w, x.description AS d,
x.amount AS a
FROM transact x
JOIN transact y ON (x.whn>=y.whn)
GROUP BY x.whn, x.description, x.amount) t
Hack 10 Converting subqueries into joins
Hack 11 Converting aggregate subqueries into joins
Hack 16 Search for a String across columns
Hack 24 Multiply Across a Result Set
Hack 25.5 Splitting and combining columns
Hack 26 Include the rows your JOIN forgot
Hack 30 Calculate the maximum/minimum of two fields
Hack 33 Get values and subtotals in one shot
Hack 50 Combine tables containing different data
Hack 51/52 Display rows as columns
Hack 55 Import Someone Else's Data
Hack 62 Issue Queries Without Using a Table
Hack 63 Generate rows without tables
Hack 72 Extract a subset of the results
Hack 78 Break it down by Range
Hack 88 Test two values from a subquery
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