# Processes by List
Analysis generated on: 4/2/2025 10:05:48 AM
---
## SQL Statement
```sql
SELECT Process.*, Metals.Density
FROM ([Process by List] LEFT JOIN Process ON [Process by List].PN = Process.PartNumber) LEFT JOIN Metals ON Process.MetalType = Metals.PartNo
WHERE (((Process.PartNumber)<>""));

```
## Dependencies
- [[Tables/Process]]
- [[Queries/Metals]]
## Parameters
- *None*
## What it does
**SQL Code Explanation**
========================

### Overview

This SQL query retrieves data from two tables, `Process` and `Metals`, joining them based on certain conditions. The query uses subqueries to first create a temporary result set containing `Process` data and then joins it with the `Metals` table.

### Breakdown of the Query

#### Subquery: `[Process by List]`

This is an ad-hoc SQL query that creates a temporary result set (`[Process by List]`) containing data from the `Process` table. The subquery uses a `LEFT JOIN` operation to include all rows from both tables.

```sql
SELECT Process.*, Metals.Density
FROM ([Process by List] LEFT JOIN Process ON [Process by List].PN = Process.PartNumber)
```

*   The subquery selects all columns (`*`) from the `Process` table and joins it with itself (noting that this might be considered redundant and inefficient).
*   It then uses a `LEFT JOIN` to include rows from both tables where the join condition is met.

#### Main Query

The main query builds upon the subquery, adding another `LEFT JOIN` operation to incorporate data from the `Metals` table.

```sql
LEFT JOIN Metals ON Process.MetalType = Metals.PartNo
```

*   This join operates on the `MetalType` column in the `Process` table and the `PartNo` column in the `Metals` table.
*   It includes rows from both tables where there is a match in these columns.

#### Filtering Condition

The query uses an inequality condition to exclude rows with empty strings (`\u003c\u003e""`).

```sql
WHERE (((Process.PartNumber)\u003c\u003e""));
```

*   This ensures that only rows with non-empty `PartNumber` values are included in the final result set.
*   The double parentheses around the comparison operation allow for the use of the NOT operator.

### Final Result

The entire query is executed as a single operation, producing the following:

*   A temporary result set containing data from both tables after applying the join conditions and filtering out empty strings.
*   The final result includes all columns (`*`) from the `Process` table, along with the density of metals for each part number.