SQL 计算 X + Y = Z

Question

New to SQL and I'm sorry if this question has already been asked. I'm looking to create a table with 3 columns X, Y, and Z where I will add the X and Y values to the table. Then I'd like to create a stored procedure that will take the row values of X and Y, add them together, and store that value as Z in my table. I'd like to be able to add X and Y values whenever I want and then run the store procedure after to calculate Z.

CREATE TABLE XYZ (
X INT NOT NULL,
Y INT NOT NULL,
Z INT NULL
);
GO

INSERT INTO XYZ (X, Y) VALUES (3, 5);
INSERT INTO XYZ (X, Y) VALUES (5, 8);
INSERT INTO XYZ (X, Y) VALUES (8, 13);

CREATE PROCEDURE CalculateZ
AS
SELECT X, Y, Z = X + Y
INTO XYZ
FROM XYZ;
GO

EXECUTE CalculateZ;
GO

INSERT INTO XYZ (X, Y) VALUES (13, 21);

EXECUTE CalculateZ;
GO

Answer 1

Try this in your stored procedure. You want an UPDATE to the original table, not an INSERT .

update XYZ
set z = x + y

Answer 2

There is no need to do that. Instead, create z as a computed column:

CREATE TABLE XYZ (
    X INT NOT NULL,
    Y INT NOT NULL,
    Z AS (X + Y)
);

Z is then calculated automatically (either when data in the row changes or when queried). There no need to update the table. No need for a stored procedure either.