Spark SQL Tutorial 12 | Null Check On Table Spark SQL | Spark Tutorial | Data Engineering

SahuStudies

20 Dec 202308:54

Summary

TLDRThis video tutorial from Sahu Studies IN introduces viewers to the process of creating and managing a non-null check table using SQL. The presenter demonstrates how to define columns, data types, and a not-null constraint. They then show how to insert records, alter the table to change column names, and drop the not-null constraint. The tutorial also covers the creation of a document fragment and the importance of not allowing null values in certain columns to maintain data integrity. The video concludes with a demonstration of how to select records from the table, emphasizing the practical application of the concepts discussed.

Takeaways

😀 The video is a tutorial on how to create a non-null check table in a database using SQL.
🔍 The presenter explains the process of defining columns, their data types, and setting a column as NOT NULL.
📝 The importance of NOT NULL constraints is highlighted to ensure data integrity during the insert process.
💾 A demonstration is provided on how to insert records into the table while adhering to the NOT NULL constraints.
🔧 The video covers the use of the ALTER TABLE command to modify the table schema, including changing column names and dropping NOT NULL constraints.
🔄 The process of updating records in the table is shown, emphasizing the need to handle NOT NULL columns correctly.
🚫 The presenter warns about the consequences of attempting to insert NULL values into NOT NULL columns and how to avoid it.
🗂️ The video includes a segment on how to remove the NOT NULL constraint from a column if necessary.
🔎 There is a discussion on how to check for the presence of NOT NULL constraints in a table using the schema information.
🛠️ The presenter uses a CREATE TABLE command to demonstrate the initial setup of a table with NOT NULL constraints.
📈 The tutorial concludes with a summary of how to manage NOT NULL constraints to maintain data consistency in a database.

Q & A

What is the purpose of the video?
-The purpose of the video is to demonstrate how to work with a 'NOT NULL' check in a table using SQL, including creating, inserting, and altering the table.
What does 'NOT NULL' mean in SQL?
-'NOT NULL' is a constraint in SQL that ensures a column must not be left empty or null when inserting or updating records in a table.
How is a table created in the video?
-A table is created using a 'CREATE TABLE' command with the help of a 'CREATE' statement, defining columns, their data types, and the 'NOT NULL' constraint where necessary.
What is a 'CREATE TABLE' command used for?
-A 'CREATE TABLE' command is used to create a new table in a database with specified columns and their data types, along with any constraints such as 'NOT NULL'.
How can records be inserted into a table with 'NOT NULL' constraints?
-Records are inserted using an 'INSERT INTO' statement, ensuring that values are provided for all 'NOT NULL' columns to avoid violation of the constraint.
What happens if you try to insert a NULL value into a 'NOT NULL' column?
-Attempting to insert a NULL value into a 'NOT NULL' column will result in an error, as the database will not allow the operation to proceed, enforcing the constraint.
How can the 'NOT NULL' constraint be removed from a column?
-The 'NOT NULL' constraint can be removed by using an 'ALTER TABLE' statement to modify the column and drop the 'NOT NULL' constraint.
What is the use of an 'ALTER TABLE' statement?
-An 'ALTER TABLE' statement is used to make changes to the structure of a table, such as adding, dropping, or modifying columns, including removing 'NOT NULL' constraints.
How can you check if a table has been created successfully?
-You can check if a table has been created successfully by using a 'SELECT' statement to query the table and see if it returns the expected structure and data.
What is the significance of the 'DROP' keyword in the context of this video?
-The 'DROP' keyword is used to remove or delete a table or a column's 'NOT NULL' constraint, allowing for structural changes to the database schema.
How can you rename a column in a table?
-A column can be renamed using an 'ALTER TABLE' statement with the appropriate syntax to change the column's name while maintaining its data and constraints.

Outlines

00:00

😀 Introduction to Creating a Table with NOT NULL Constraints

This paragraph introduces the process of creating a table in a database using SQL. It explains the steps to define a table with six columns, including data types and the NOT NULL constraint to ensure data integrity. The speaker also mentions inserting records into the table and the importance of the NOT NULL constraint for certain columns to prevent the insertion of null values.

05:01

😀 Inserting Records and Altering Table Structure

The second paragraph discusses inserting records into the previously created table and the potential issues that may arise if null values are not allowed for certain columns. It also covers how to alter the table structure by adding or changing column names and dropping the NOT NULL constraint if necessary. The speaker emphasizes the importance of careful planning when altering tables and the steps to successfully update the table schema.

Mindmap

Keywords

💡No Null Check

The term 'No Null Check' refers to a database constraint that ensures a column cannot contain null values. In the context of the video, it is a key concept for defining the integrity of the data within a table, ensuring that important fields are always filled out. The script mentions this in relation to creating a table and inserting records, emphasizing the importance of not allowing null values in certain columns.

💡Create Table

The 'Create Table' command is a SQL statement used to define a new table in a database with specified columns and data types. The video script discusses creating a table with the help of a 'Create Table' command, outlining columns and setting not null constraints to ensure data integrity. This is fundamental in database management for organizing and storing data effectively.

💡Column

In the script, 'Column' refers to a vertical segment of a table that holds data of a specific format or type. The video explains defining columns with names and data types, and setting constraints like 'No Null Check'. This is essential for structuring data within a database and ensuring that each column adheres to the required format.

💡Data Type

The 'Data Type' in the context of the video script defines the kind of values a column can hold, such as 'String', 'Integer', etc. The script mentions defining data types for columns when creating a table, which is crucial for enforcing the correct format and operations on the data stored in the database.

💡Insert Record

The term 'Insert Record' is used in the script to describe the action of adding a new row of data to a database table. The video explains the process of inserting data into a table, ensuring that the 'No Null Check' constraint is respected, which means all fields must be filled out with valid data.

💡Constraint

A 'Constraint' in the script represents a rule in a database that limits the type of data that can be inserted into a table. The video discusses implementing 'No Null Check' as a constraint to maintain data integrity and ensure that certain columns always have valid, non-null values.

💡Alter Table

'Alter Table' is a SQL command used to make changes to the structure of an existing table, such as adding or dropping columns. The video script touches on altering a table, which is an important concept when the structure of the data needs to be modified after the table has been created.

💡Drop Constraint

The 'Drop Constraint' action, as mentioned in the script, is used to remove a previously defined constraint from a table. This is part of the video's discussion on modifying table structures and could be necessary if the data requirements change over time.

💡Data Integrity

Data integrity refers to the accuracy and consistency of data in a database. The video script emphasizes the importance of data integrity by discussing 'No Null Check' constraints and ensuring that every record inserted into the table meets the defined rules and formats.

💡Database Management

The overarching theme of the video script is 'Database Management', which involves the creation, modification, and maintenance of database structures and data. The script provides examples of creating tables, inserting data, and applying constraints, all of which are key aspects of managing a database effectively.

💡Script

In the context of the video, 'Script' refers to the text being read or followed during the video presentation. The script contains technical terms and instructions related to database operations, serving as the foundation for the video's educational content on database management.

Highlights

Introduction to Sahu Studies In, discussing how to put a not null check in a table using SQL.

Creating a table with the help of a CREATE TABLE command, defining six columns and their data types.

One of the columns named 'name' is set as NOT NULL to prevent null values.

Demonstration of inserting a record into the table without null values for the 'name' column.

Explanation of how the NOT NULL constraint is enforced during the insert process.

Capturing the output to show that records have been successfully inserted into the table.

Creating a document fragment to implement NOT NULL check over a column.

Altering a table to change the column name and dropping the NOT NULL condition.

Using the ALTER TABLE statement to modify the table structure and constraints.

Dropping the NOT NULL constraint from the 'name' column to allow null values.

Explanation of how to remove the NOT NULL check using the ALTER TABLE command.

Providing training on table creation and manipulation with NOT NULL constraints.

Demonstration of creating a table with NOT NULL check using a running cluster.

Connecting to a database to create a table with NOT NULL constraints if not already existing.

Inserting records into the table with NOT NULL values for specific columns.

Ensuring that the insert statement does not take place if null values are provided.

Duplicating the NOT NULL check by setting it for another column in the table.

Finalizing the process by showing the successfully created table with NOT NULL constraints.

Encouraging viewers to like, subscribe, and comment on the video for more content.