SQL update query to get values by joining 3 tables - sql

Question

Please help me to write update query for below. I am using SQL server 2014.
Requirement: Update Table C based on project Id, get corresponding 'Answer_weightage' values for corresponding project ID and from latest record. Table A 'Latest'= 'Yes' means it is a latest record. Based on 'Link_Id' Table A and B are linked. Table A and C are linked based on 'Project_Id'
Table A:
<table>
<tr>
<th>
Request Type |
</th>
<th>Project ID | </th>
<th>Latest |</th>
<th> Link_ID</th>
</tr>
<tr>
-----------------------------------------------
</tr>
<tr>
<td>
a
</td>
<td>1000</td> <td>No</td> <td>1</td>
</tr>
<tr>
<td>b</td> <td>1005</td> <td>Yes </td> <td>2</td>
<tr>
<td>123</td> <td>1000</td><td>Yes </td> <td>4</td></tr>
<tr>
<td>c </td><td>1005</td> <td>No</td> <td>3</td></tr>
</table>
Table B
<table>
<tr>
<th>
Question</th> <th>Description</th> <th>Answer_weightage</th> <th>Link_ID
</th>
</tr>
<tr><td>
6 </td><td>Question6 </td><td>0</td> <td>2</td>
</tr>
<tr>
<td>2</td> <td>Question2</td> <td>5</td> <td>4</td></tr>
<tr>
<td>3</td> <td>Question3 </td><td>5</td> <td>4</td></tr>
<tr>
<td>4</td> <td>Question4</td><td> 5</td> <td>4</td></tr>
<tr>
<td>5 </td><td>Question5 </td><td>2</td> <td>4</td></tr>
<tr>
<td>6</td> <td>Question6 </td><td>2 </td><td>4</td></tr>
<tr>
<td>7</td> <td>Question7</td> <td>9 </td><td>4</td></tr>
<tr>
<td>1</td> <td>Question1 </td><td>5</td> <td>1</td></tr>
<tr>
<td>2</td> <td>Question2 </td><td>9</td> <td>1</td></tr>
<tr>
<td>3 </td><td>Question3 </td><td>5</td><td> 1</td></tr>
<tr>
<td>4</td> <td>Question4</td> <td>2 </td><td>1</td></tr>
<tr>
<td>5</td> <td>Question5</td> <td>5 </td><td>1</td></tr>
<tr>
<td>6</td> <td>Question6</td> <td>5 </td><td>1</td></tr>
<tr>
<td>7</td> <td>Question7</td> <td>2</td> <td>1</td></tr>
<tr>
<td>1</td> <td>Question1</td> <td>2 </td><td>2</td></tr>
<tr>
<td>2</td> <td>Question2</td> <td>0 </td><td>2</td></tr>
<tr>
<td>3 </td><td>Question3</td> <td>9 </td><td>2</td></tr>
<tr>
<td>4</td> <td>Question4 </td><td>9</td><td> 2</td></tr>
<tr>
<td>5 </td><td>Question5 </td><td>9</td><td> 2</td></tr>
<tr>
<td>7 </td><td>Question7</td> <td>5 </td><td>2</td></tr>
<tr>
<td>1</td> <td>Question1</td><td> 2</td> <td>4</td></tr>
</table>
Table C:
<table>
<tr>
<th>Project ID</th>
<th>Question1</th>
<th>Question2</th>
<th>Question3</th>
<th>Question4</th>
<th>Question5</th>
<th>Question6</th>
<th>Question7</th>
</tr>
<tr>
<td>1000</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr>
<td>1005</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
</table>
Desired Result (in Table C):
<table>
<tr>
<th>Project ID</th>
<th>Question1</th>
<th>Question2</th>
<th>Question3</th>
<th>Question4</th>
<th>Question5</th>
<th>Question6</th>
<th>Question7</th>
</tr>
<tr>
<td>1000</td>
<td>2</td>
<td>5</td>
<td>5</td>
<td>5</td>
<td>2</td>
<td>2</td>
<td>9</td>
</tr>
<tr>
<td>1005</td>
<td>2</td>
<td>0</td>
<td>9</td>
<td>9</td>
<td>0</td>
<td>9</td>
<td>5</td>
</tr>
</table>

Answer 1

You want to update question1 of Table C, set the value equal to Answer_weightage selected from B where b.Description = 'Question1' and linkId = (Link_Id from A where latest='YES' and has same projectId as C).
Update C set C.Question1 =
(select Answer_weightage
from B
where Description='Question1' and Link_ID =
(select Link_ID
from A
where A.ProjectID = C.ProjectID and Latest='Yes'))