Combine tables

Combine tables containing different data

schema:scott

DROP TABLE staff;
DROP TABLE student;

 CREATE TABLE staff(
  staffid INTEGER,
  email VARCHAR(20),
  name VARCHAR(20),
  salary INTEGER );
INSERT INTO staff VALUES (0173,'stan@bos.edu','Stern','Stan',99000);
INSERT INTO staff VALUES (0101,'ali@bos.edu','Aloof','Alison',30000);
CREATE TABLE student (
  id INTEGER,
  fname VARCHAR(20),
  lname VARCHAR(20),
  gpa INTEGER );
INSERT INTO student VALUES (1007,'Peter','Perfect',590);
INSERT INTO student VALUES (1008,'Donald','Dunce',220);

You can use UNION when you have two tables you want to combine but that contain different data.

You will have to make the two tables agree before you can do the UNION though

In this example a staff table and a student table are combined

SELECT 'F' || staffid id, name name,
email email, salary salary, NULL gpa, 'Staff' species
FROM staff
UNION
SELECT 'S' || id id, lname || ',' || fname name,
id || '@bos.edu' email, NULL salary, gpa gpa,
'Student' species
FROM student

SELECT 'F' || staffid id, name name,
email email, salary salary, NULL gpa, 'Staff' species
FROM staff
UNION
SELECT 'S' || id id, lname || ',' || fname name,
id || '@bos.edu' email, NULL salary, gpa gpa,
'Student' species
FROM student

SELECT CONCAT('F',staffid) id, name name,
email email, salary salary, NULL gpa, 'Staff' species
FROM staff
UNION
SELECT CONCAT('S',id) id, CONCAT(lname,',',fname) name,
CONCAT(id,'@bos.edu') email, NULL salary, gpa gpa,
'Student' species
FROM student

SELECT 'F' + staffid id, name name,
email email, salary salary, NULL gpa, 'Staff' species
FROM staff
UNION
SELECT 'S' + id id, lname + ',' + fname name,
id + '@bos.edu' email, NULL salary, gpa gpa,
'Student' species
FROM student

SELECT 'F' + staffid id, name name,
email email, salary salary, NULL gpa, 'Staff' species
FROM staff
UNION
SELECT 'S' + id id, lname + ',' + fname name,
id + '@bos.edu' email, NULL salary, gpa gpa,
'Student' species
FROM student

SQL HACKS

Hack 10 Converting subqueries into joins

Hack 11 Converting aggregate subqueries into joins

Hack 14 Generate Combinations

Hack 16 Search for a String across columns

Hack 24 Multiply Across a Result Set

Hack 25 Keep a running total

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 70 Combine your queries

Hack 72 Extract a subset of the results

Hack 78 Break it down by Range

Hack 88 Test two values from a subquery

Hack 98 Find and stop long running queries

Hack 100 Run SQL from a Web Page