Cannot figure out how to write MySQL Query - mysql

Question

I am trying to write a MySQL select statement which will use table1 and table2 to generate a table3.
table1
id
Month
Year
Name
Length
Breath
1
January
2002
Square
5
2
2
February
2003
Circle
6
3
3
March
2004
Cylinder
7
4
4
April
2005
Cube
8
5
5
May
2006
Quadilateral
9
6
table2
id
Month
Year
Name
Frequency
Area
Volume
1
January
2002
Square
1
20
50
2
Febrauy
2003
Circle
2
25
55
3
March
2004
Cylinder
3
Null
60
4
April
2005
Cube
4
35
65
5
May
2006
Quadilateral
5
40
Null
table3 the generated table should be like this.
Name
Type
Month
Year
Length
Breath
Frequency
Volume/Area
Cum_Area
Cum_Volume
Area
Volume
Square
2d
January
2002
5
2
1
2.5
20
50
20
50
Circle
2d
February
2003
6
3
2
2.2
45
105
25
55
Cylinder
3d
March
2004
7
4
3
2
45
165
30
60
Cube
3d
April
2005
8
5
4
1.86
80
230
35
65
Quadilateral
4d
May
2006
9
6
5
1.75
120
230
40
70
In the statements I've tried whenever the cumulative column encounters the first null value, every row from then on is null.
Also, how do I write the type column? I'd like square and circle to be '2d'; cube and cylinder to be '3d' and Quadrilateral to be '4d'.
Table 1 and 2 have the Name, Month and Year column in common.

Answer 1

I don't finish to understand what is your logic or why you don't have ids on the second table. But assuming what you write, this is a SUGGESTION.
Update your question I'll glad to update my answer.
Assuming null means 0:
SELECT
table1.Name,
CASE table1.Name
WHEN Square THEN '2d'
WHEN Circle THEN '2d'
WHEN Cylinder THEN '3d'
WHEN Cube THEN '3d'
WHEN Quadilateral THEN '4d'
END as Type,
table1.Month,
table1.Year,
table1.Length,
table1.Breath,
table2.Frequency,
(IFNULL(table2.Volume,0) / IFNULL(table2.Area,0)) as 'Volume/Area',
//I don't understand what do you need in this field,
//I don't understand what do you need in this field,
table2.Area,
table2.Volume
FROM table1
JOIN table2
ON table1.Name = table2.Name AND table1.Month = table2.Month AND table1.Year = table2.Year