Question

I have three tables and I want to update all values for a particular type to the same value:

table1:
id, ValueType

table2:
id, Value

table3:
id, fkValueTypeId, fkValueId

fkValueType references ID in table1. fkValue references ID in Table2

I am trying to set all Speed values to the same value:

i.e.

Table1:
0, speed
1, age
2, colour

Table2:
0, 10
1, 20
2, 30
3, 40
4, 18
5, 18
6, blue
7, black
8, orange
9, 33
10, 34
11, 35

Table3:
0, 0, 0      --Speed = 10
1, 0, 0      --Speed = 20
2, 0, 0      --Speed = 30
3, 0, 0      --Speed = 40
4, 1, 1      --Age = 18
5, 1, 1      --Age = 18
6, 2, 2      --Colour = Blue
7, 2, 2      --Colour = Black
8, 2, 2      --Colour = Orange
9, 0, 9      --Speed = 33
10, 0, 10    --Speed = 34
11, 0, 11    --Speed = 35

What I want to do is Update Speed to ’55’ for all Speed entries in the tables so that table2 looks like this:

Table2:
0, 55
1, 55
2, 55
3, 55
4, 18
5, 18
6, blue
7, black
8, orange
9, 55
10, 55
11, 55

Hope this makes sense. I am not sure on the syntax and can do it using a loop but wondered if there is a better way (which I am sure there is!).

Thank you

Answer 1

A rewrite of @hobodave’s answer:

UPDATE table2
SET Value = 55
FROM table2
JOIN table3 ON table3.fkValueId = table2.id
WHERE table3.fkValueTypeId = 0