# Data Query Language

### The SQL SELECT Statement

The SELECT statement is used to retrieve data from a database.

The data returned is stored in a result table, called the result-set.

**Basic Syntax:**

```sql
SELECT column1,column2 FROM table_name 
column1 , column2: names of the fields of the table
table_name: from where we want to fetch
```

### Demo Database

Below is a selection from the "Consumer" table in a sample database:

![](https://826093633-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LS8lPNzCGPR5-DLbGXv%2F-LSDdfpWrETNVIuqLFRG%2F-LSDgFPvCHfuSDmjO4_w%2Fimage.png?alt=media\&token=aed640ac-2618-4b64-b188-8b2615077c24)

### SELECT Column 

The following SQL statement selects the "Customer Name" and "City" columns from the "Consumer" table:

```sql
SELECT CustomerName, City FROM Consumer;
```

### SELECT \*

 The following SQL statement selects all the columns from the "Consumer" table:

```sql
SELECT * FROM Consumer;
```

### SQL Order of Execution

The SQL order of execution defines the order in which the clauses of a query are evaluated. Some of the most common query challenges I run into could be easily avoided with a clearer understanding of the SQL order of execution, sometimes called the order of operations. Understanding query order can help you diagnose why a query won't run, and even more frequently will help you optimize your queries to run faster.\
\
In today's modern world, SQL query planners can do all sorts of tricks to make queries run more efficiently, but they must always reach the same final answer as a query that is executed per the standard order of execution. This order is:

![](https://826093633-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LS8lPNzCGPR5-DLbGXv%2F-LTNso28JJSh8_bE61mw%2F-LTNt1yNKMK2VTSLcct7%2Fimage.png?alt=media\&token=ed850f2b-342e-4f26-a65c-94625fab0392)