What Is The Primary Key In SQL? The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields). Why primary key
How Do I Rename A Column In PostgreSQL? The syntax to rename a column in a table in PostgreSQL (using the ALTER TABLE statement) is: ALTER TABLE table_name RENAME COLUMN old_name TO new_name; table_name . The name of the table to modify. How do I rename a column in PostgreSQL query? First, specify the name
How Do I Drop A Column In Pyspark? In pyspark the drop() function can be used to remove values/columns from the dataframe. thresh – This takes an integer value and drops rows that have less than that thresh hold non-null values. By default it is set to ‘None’. How do I drop a column in