How to assign column value to a variable within mySQL script ? - mysql

I have the following script but it returns null all the time.
SELECT
#PRICE_LARGE_PRICE = PRICE_LARGE_PRICE,
#PRICE_SMALL_PRICE = PRICE_SMALL_PRICE
FROM
prices
WHERE
PRICE_LISTING_ID = 60;
SET #ITEM_PRICE = (CASE Size WHEN GivenLargeSizeName THEN #PRICE_LARGE_PRICE
WHEN GivenSmallSizeName THEN #PRICE_SMALL_PRICE
ELSE null
END);
The issue here is
#PRICE_LARGE_PRICE = PRICE_LARGE_PRICE,
#PRICE_SMALL_PRICE = PRICE_SMALL_PRICE
table returns PRICE_LARGE_PRICE & PRICE_SMALL_PRICE correctly but the assignment does not work. Hence CASE fails.
Any help is appreciated.

You need to use SELECT ... INTO:
SELECT PRICE_LARGE_PRICE, PRICE_SMALL_PRICE
INTO #PRICE_LARGE_PRICE, #PRICE_SMALL_PRICE
FROM prices
WHERE PRICE_LISTING_ID = 60;
Note that you need to ensure that the query only returns one row of data, using LIMIT 1 if necessary.

SELECT
#PRICE_LARGE_PRICE:=PRICE_LARGE_PRICE,
#PRICE_SMALL_PRICE:=PRICE_SMALL_PRICE
FROM
prices
WHERE
PRICE_LISTING_ID = 60;
just add colon before equal sign in mysql

Related

How could I select a column based on another column in mySQL?

The following script works fine. But I want to write it in one line rather than three lines. 'Size" is passed from my main program and its used here to test. Simply I want to get Price based on size.
Table columns :
LISTING_ID, PRICE_LARGE_PRICE, PRICE_SMALL_PRICE.
SET #Size = 'SMALL';
SELECT
PRICE_LARGE_PRICE,PRICE_SMALL_PRICE
INTO
#PRICE_LARGE_PRICE,#PRICE_SMALL_PRICE
FROM
prices
WHERE
PRICE_LISTING_ID = 60;
SET #ITEM_PRICE = (CASE #Size WHEN 'REGULAR' THEN #PRICE_LARGE_PRICE
WHEN 'SMALL' THEN #PRICE_SMALL_PRICE
ELSE null
END);
SELECT #ITEM_PRICE;
Any help is appreciated.
Following may work.
SET #Size = 'SMALL';
SELECT
PRICE_LARGE_PRICE,
PRICE_SMALL_PRICE,
CASE WHEN #Size = 'REGULAR' THEN PRICE_LARGE_PRICE
WHEN #Size = 'SMALL' THEN PRICE_SMALL_PRICE
END AS ITEM_PRICE
INTO
#PRICE_LARGE_PRICE,
#PRICE_SMALL_PRICE,
#ITEM_PRICE
FROM
prices
WHERE
PRICE_LISTING_ID = 60;
I think you want
SELECT
IF(#size == 'SMALL', PRICE_SMALL_PRICE, PRICE_LARGE_PRICE) AS ITEM_PRICE
FROM prices;

MYSQL - UPDATE multiple fields based on single CASE statement

OBJECTIVE
I am looking for a way to update one or both fields using the same CASE statement
UPDATE vendor
SET special_cost =
(
CASE
WHEN
cost > 14
THEN
14
ELSE
SET special_cost = cost, cost = 14
END
)
WHERE upc = '12345678912345'
LOGIC
This is some logic that explains what I want to happen above.
if ($cost > 14) {
$special_cost = 14;
} else {
$special_cost = $cost;
$cost = 14;
}
It does not seem that there is a way to do this with a single CASE statement. Perhaps, this can be done with the mysql IF statement?
You are referring to case expressions not case statements.
You appear to want something like this:
UPDATE vendor
SET special_cost = GREATEST(cost, 14),
cost = 14
WHERE upc = '12345678912345';

What's wrong with this SQL query WHERE AND clause?

Previously, this was working:
$patient_story_set_photos = $wpdb->get_results('SELECT * FROM wp_before_after WHERE patientID = '.$post->ID.' AND patient_display = 1');
However, when I try to add another AND condition like this:
$patient_story_set_photos = $wpdb->get_results('SELECT * FROM wp_before_after WHERE patientID = '.$post->ID.' AND patient_display = 1 AND period_taken = '.$set->period_taken);
I get the following error on screen:
WordPress database error: [Unknown column '1hour' in 'where clause']
SELECT * FROM wp_before_after WHERE patientID = 8175 AND patient_display = 1 AND period_taken = 1hour
Can't see why there's a problem, are you not allowed to use multiple AND conditions in SQL?
The problem is not the AND, the problem is your 1hour, 1hour unquoted means a reference to an object (database, table) named 1hour, you need to quote '1hour'.
If you write
SELECT * FROM wp_before_after
WHERE patientID = 8175
AND patient_display = 1
AND period_taken = '1hour'
you will compare the field periodtaken to a string (CHAR,VARCHAR,TEXT) equal to '1hour'.
I assume period_taken is a field typed CHAR,VARCHAR or TEXT
Before anything, DO NOT CONCATENATE SQL STRINGS nowadays it is a MUST (see how to do it properly https://stackoverflow.com/a/60496/3771219)
The problem you are facing is because, I presume, that the period_taken field is some sort of Char/Varchar/String field and when you are filtering by a "Stringy" field you must sorround your literals values with single quotes:
SELECT *
FROM wp_before_after
WHERE patientID = 8175
AND patient_display = 1
AND period_taken = '1hour'
Hope this help

MySQL user-defined function returns incorrect value when used in a SELECT statement

I met a problem when calling a user-defined function in MySQL. The computation is very simple but can't grasp where it went wrong and why it went wrong. Here's the thing.
So I created this function:
DELIMITER //
CREATE FUNCTION fn_computeLoanAmortization (_empId INT, _typeId INT)
RETURNS DECIMAL(17, 2)
BEGIN
SET #loanDeduction = 0.00;
SELECT TotalAmount, PeriodicDeduction, TotalInstallments, DeductionFlag
INTO #totalAmount, #periodicDeduction, #totalInstallments, #deductionFlag
FROM loans_table
WHERE TypeId = _typeId AND EmpId = _empId;
IF (#deductionFlag = 1) THEN
SET #remaining = #totalAmount - #totalInstallments;
IF(#remaining < #periodicDeduction) THEN
SET #loanDeduction = #remaining;
ELSE
SET #loanDeduction = #periodicDeduction;
END IF;
END IF;
RETURN #loanDeduction;
END;//
DELIMITER ;
If I call it like this, it works fine:
SELECT fn_computeLoanAmortization(3, 4)
But if I call it inside a SELECT statement, the result becomes erroneous:
SELECT Id, fn_computeLoanAmortization(Id, 4) AS Amort FROM emp_table
There's only one entry in the loans_table and the above statement should only result with one row having value in the Amort column but there are lots of random rows with the same Amort value as the one with the matching entry, which should not be the case.
Have anyone met this kind of weird dilemma? Or I might have done something wrong from my end. Kindly enlighten me.
Thank you very much.
EDIT:
By erroneous, I meant it like this:
loans_table has one record
EmpId = 1
TypeId = 2
PeriodicDeduction = 100
TotalAmount = 1000
TotalInstallments = 200
DeductionFlag = 1
emp_table has several rows
EmpId = 1
Name = Paolo
EmpId = 2
Name = Nikko
...
EmpId = 5
Name = Ariel
when I query the following statements, I get the correct value:
SELECT fn_computeLoanAmortization(1, 2)
SELECT Id, fn_computeLoanAmortization(Id, 2) AS Amort FROM emp_table WHERE EmpId = 1
But when I query this statement, I get incorrect values:
SELECT Id, fn_computeLoanAmortization(Id, 2) AS Amort FROM emp_table
Resultset would be:
EmpId | Amort
--------------------
1 | 100
2 | 100 (this should be 0, but the query returns 100)
3 | 100 (same error here)
...
5 | 100 (same error here up to the last record)
Inside your function, the variables you use to retrieve the values from the loans_table table are not local variables local to the function but session variables. When the select inside the function does not find any row, those variables still have the same values as from the previous execution of the function.
Use real local variables instead. In order to do that, use the variables names without # as a prefix and declare the variables at the beginning of the function. See this answer for more details.
I suspect the problem is that the variables in the INTO are not re-set when there is no matching row.
Just set them before the INTO:
BEGIN
SET #loanDeduction = 0.00;
SET #totalAmount = 0;
SET #periodicDeduction = 0;
SET #totalInstallments = 0;
SET #deductionFlag = 0;
SELECT TotalAmount, PeriodicDeduction, TotalInstallments, DeductionFlag
. . .
You might just want to set them to NULL.
Or, switch your logic to use local variables:
SET v_loanDeduction = 0.00;
SET v_totalAmount = 0;
SET v_periodicDeduction = 0;
SET v_totalInstallments = 0;
SET v_deductionFlag = 0;
And so on.

SQL Server 2008: Error converting data type nvarchar to float

Presently troubleshooting a problem where running this SQL query:
UPDATE tblBenchmarkData
SET OriginalValue = DataValue, OriginalUnitID = DataUnitID,
DataValue = CAST(DataValue AS float) * 1.335
WHERE
FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND ZEGCodeID IN
(SELECT ZEGCodeID FROM tblZEGCode
WHERE(ZEGCode = 'C004') OR
(LEFT(ZEGParentCode, 4) = 'C004'))
Results in the following error:
Msg 8114, Level 16, State 5, Line 1
Error converting data type nvarchar to float.
The really odd thing is, if I change the UPDATE to SELECT to inspect the values that are retrieved are numerical values:
SELECT DataValue
FROM tblBenchmarkData
WHERE FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND ZEGCodeID IN
(SELECT ZEGCodeID
FROM tblZEGCode WHERE(ZEGCode = 'C004') OR
(LEFT(ZEGParentCode, 4) = 'C004'))
Here are the results:
DataValue
2285260
1205310
Would like to use TRY_PARSE or something like that; however, we are running on SQL Server 2008 rather than SQL Server 2012. Does anyone have any suggestions? TIA.
It would be helpful to see the schema definition of tblBenchmarkData, but you could try using ISNUMERIC in your query. Something like:
SET DataValue = CASE WHEN ISNUMERIC(DataValue)=1 THEN CAST(DataValue AS float) * 1.335
ELSE 0 END
Order of execution not always matches one's expectations.
If you set a where clause, it generally does not mean the calculations in the select list will only be applied to the rows that match that where. SQL Server may easily decide to do a bulk calculation and then filter out unwanted rows.
That said, you can easily write try_parse yourself:
create function dbo.try_parse(#v nvarchar(30))
returns float
with schemabinding, returns null on null input
as
begin
if isnumeric(#v) = 1
return cast(#v as float);
return null;
end;
So starting with your update query that's giving an error (please forgive me for rewriting it for my own clarity):
UPDATE B
SET
OriginalValue = DataValue,
OriginalUnitID = DataUnitID,
DataValue = CAST(DataValue AS float) * 1.335
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
I think you'll find that a SELECT statement with exactly the same expressions will give the same error:
SELECT
OriginalValue,
DataValue NewOriginalValue,
OriginalUnitID,
DataUnitID OriginalUnitID,
DataValue,
CAST(DataValue AS float) * 1.335 NewDataValue
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
This should show you the rows that can't convert:
SELECT
B.*
FROM
dbo.tblBenchmarkData B
INNER JOIN dbo.tblZEGCode Z
ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
AND (
Z.ZEGCode = 'C004' OR
Z.ZEGParentCode LIKE 'C004%'
)
AND IsNumeric(DataValue) = 0
-- AND IsNumeric(DataValue + 'E0') = 0 -- try this if the prior doesn't work
The trick in the last commented line is to tack on things to the string to force only valid numbers to be numeric. For example, if you wanted only integers, IsNumeric(DataValue + '.0E0') = 0 would show you those that aren't.