This topic explains how to add a calculated column to a query using SQL expressions.
Example: Add a Calculated Column
In this example we use SQL to add a column to a query based on the Physical Exam dataset. The column will display
"Pulse Pressure" -- the change in blood pressure between contractions of the heart muscle, calculated as the difference between systolic and diastolic blood pressures.
Create a Query
- Navigate to Admin > Developer Links > Schema Browser.
- Select a schema to base the query on. (For this example, select the study schema.)
- Click Create New Query.
- Create a query based on some dataset. (For this example, select the Physical Exam dataset.)
Modify the SQL Source
- Adding the following SQL will create a column with the calculated value we seek:
"Physical Exam".SystolicBloodPressure-"Physical Exam".DiastolicBloodPressure as PulsePressure
- The final SQL source should look like the following:
SELECT "Physical Exam".ParticipantId,
"Physical Exam".date,
"Physical Exam".Weight_kg,
"Physical Exam".Temp_C,
"Physical Exam".SystolicBloodPressure,
"Physical Exam".DiastolicBloodPressure,
"Physical Exam".Pulse,
"Physical Exam".Respirations,
"Physical Exam".Signature,
"Physical Exam".Pregnancy,
"Physical Exam".Language,
"Physical Exam".SystolicBloodPressure-"Physical Exam".DiastolicBloodPressure as PulsePressure
FROM "Physical Exam"
- Click Save and Finish.
- Notice that LabKey Server has made a best guess at the correct column label, adding a space to "Pulse Pressure".
