SQL
Examples
```sql
CREATE TABLE integers (i INTEGER, j INTEGER);
```  
Add a new column with name `k` to the table `integers`, it will be filled with the default value `NULL`:  
```sql
ALTER TABLE integers ADD COLUMN k INTEGER;
```  
Add a new column with name `l` to the table integers, it will be filled with the default value 10:  
```sql
ALTER TABLE integers ADD COLUMN l INTEGER DEFAULT 10;
```  
Drop the column `k` from the table integers:  
```sql
ALTER TABLE integers DROP k;
```  
Change the type of the column `i` to the type `VARCHAR` using a standard cast:  
```sql
ALTER TABLE integers ALTER i TYPE VARCHAR;
```  
Change the type of the column `i` to the type `VARCHAR`, using the specified expression to convert the data for each row:  
```sql
ALTER TABLE integers ALTER i SET DATA TYPE VARCHAR USING concat(i, '_', j);
```  
Set the default value of a column:  
```sql
ALTER TABLE integers ALTER COLUMN i SET DEFAULT 10;
```  
Drop the default value of a column:  
```sql
ALTER TABLE integers ALTER COLUMN i DROP DEFAULT;
```  
Make a column not nullable:  
```sql
ALTER TABLE integers ALTER COLUMN i SET NOT NULL;
```  
Drop the not-`NULL` constraint:  
```sql
ALTER TABLE integers ALTER COLUMN i DROP NOT NULL;
```  
Rename a table:  
```sql
ALTER TABLE integers RENAME TO integers_old;
```  
Rename a column of a table:  
```sql
ALTER TABLE integers RENAME i TO ii;
```  
Add a primary key to a column of a table:  
```sql
ALTER TABLE integers ADD PRIMARY KEY (i);
```