Course Content
Intermediate SQL
Intermediate SQL
ALTER and INSERT Operations
In the previous chapter, we learned how to create tables.
But let's imagine a situation where we need to add a column to an existing table. It would be quite foolish to delete the table (especially if it already contains some data) and then create a new table, filling it again with data.
Therefore, in this chapter, we will look at the ALTER
operation.
Let's see how to use this operation:
As you can see, this is the script for creating a table from the previous chapter.
Next, there are two ALTER
operations. The first operation adds a price
column to the table, setting the default value to 300
for this column. The second operation removes this column.
The syntax is extremely simple:
The syntax is actually quite simple.
Note
Using the
ALTER
statement, you can perform various schema-level operations on a table, such as adding or removing constraints, renaming, changing data types, and adding or dropping indexes.
Let's move on to another operation, namely the insertion operation.
INSERT
Data insertion in SQL can be done using the INSERT
statement.
To use INSERT, we need to specify into which columns we want to add values.
Here's what the syntax of this statement looks like:
You might have correctly noticed that this is a snippet of the script from the previous chapter, where data is inserted into the library
table.
Let's break down what's happening here:
- First, the keywords
INSERT INTO
are written, followed by thetable_name
into which the data will be inserted; - Then, parentheses are opened, and the column names into which the data will be inserted are specified; in our case, there are 4 columns;
- After that, the keyword
VALUES
is written, and parentheses are opened where the data will be written; - The data should be written in the same order as the column names were specified, and the data types must be observed. You cannot insert an integer value into a column with the
VARCHAR
data type; - The parentheses are closed, and a comma is placed, thus filling one row. You can fill as many rows as you deem necessary using this method.
In summary, the generic syntax of the INSERT
statement looks like this:
Don't forget about the semicolon in the end!
Let's move on to the task!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Everything was clear?
ALTER and INSERT Operations
In the previous chapter, we learned how to create tables.
But let's imagine a situation where we need to add a column to an existing table. It would be quite foolish to delete the table (especially if it already contains some data) and then create a new table, filling it again with data.
Therefore, in this chapter, we will look at the ALTER
operation.
Let's see how to use this operation:
As you can see, this is the script for creating a table from the previous chapter.
Next, there are two ALTER
operations. The first operation adds a price
column to the table, setting the default value to 300
for this column. The second operation removes this column.
The syntax is extremely simple:
The syntax is actually quite simple.
Note
Using the
ALTER
statement, you can perform various schema-level operations on a table, such as adding or removing constraints, renaming, changing data types, and adding or dropping indexes.
Let's move on to another operation, namely the insertion operation.
INSERT
Data insertion in SQL can be done using the INSERT
statement.
To use INSERT, we need to specify into which columns we want to add values.
Here's what the syntax of this statement looks like:
You might have correctly noticed that this is a snippet of the script from the previous chapter, where data is inserted into the library
table.
Let's break down what's happening here:
- First, the keywords
INSERT INTO
are written, followed by thetable_name
into which the data will be inserted; - Then, parentheses are opened, and the column names into which the data will be inserted are specified; in our case, there are 4 columns;
- After that, the keyword
VALUES
is written, and parentheses are opened where the data will be written; - The data should be written in the same order as the column names were specified, and the data types must be observed. You cannot insert an integer value into a column with the
VARCHAR
data type; - The parentheses are closed, and a comma is placed, thus filling one row. You can fill as many rows as you deem necessary using this method.
In summary, the generic syntax of the INSERT
statement looks like this:
Don't forget about the semicolon in the end!
Let's move on to the task!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Everything was clear?
ALTER and INSERT Operations
In the previous chapter, we learned how to create tables.
But let's imagine a situation where we need to add a column to an existing table. It would be quite foolish to delete the table (especially if it already contains some data) and then create a new table, filling it again with data.
Therefore, in this chapter, we will look at the ALTER
operation.
Let's see how to use this operation:
As you can see, this is the script for creating a table from the previous chapter.
Next, there are two ALTER
operations. The first operation adds a price
column to the table, setting the default value to 300
for this column. The second operation removes this column.
The syntax is extremely simple:
The syntax is actually quite simple.
Note
Using the
ALTER
statement, you can perform various schema-level operations on a table, such as adding or removing constraints, renaming, changing data types, and adding or dropping indexes.
Let's move on to another operation, namely the insertion operation.
INSERT
Data insertion in SQL can be done using the INSERT
statement.
To use INSERT, we need to specify into which columns we want to add values.
Here's what the syntax of this statement looks like:
You might have correctly noticed that this is a snippet of the script from the previous chapter, where data is inserted into the library
table.
Let's break down what's happening here:
- First, the keywords
INSERT INTO
are written, followed by thetable_name
into which the data will be inserted; - Then, parentheses are opened, and the column names into which the data will be inserted are specified; in our case, there are 4 columns;
- After that, the keyword
VALUES
is written, and parentheses are opened where the data will be written; - The data should be written in the same order as the column names were specified, and the data types must be observed. You cannot insert an integer value into a column with the
VARCHAR
data type; - The parentheses are closed, and a comma is placed, thus filling one row. You can fill as many rows as you deem necessary using this method.
In summary, the generic syntax of the INSERT
statement looks like this:
Don't forget about the semicolon in the end!
Let's move on to the task!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!
Everything was clear?
In the previous chapter, we learned how to create tables.
But let's imagine a situation where we need to add a column to an existing table. It would be quite foolish to delete the table (especially if it already contains some data) and then create a new table, filling it again with data.
Therefore, in this chapter, we will look at the ALTER
operation.
Let's see how to use this operation:
As you can see, this is the script for creating a table from the previous chapter.
Next, there are two ALTER
operations. The first operation adds a price
column to the table, setting the default value to 300
for this column. The second operation removes this column.
The syntax is extremely simple:
The syntax is actually quite simple.
Note
Using the
ALTER
statement, you can perform various schema-level operations on a table, such as adding or removing constraints, renaming, changing data types, and adding or dropping indexes.
Let's move on to another operation, namely the insertion operation.
INSERT
Data insertion in SQL can be done using the INSERT
statement.
To use INSERT, we need to specify into which columns we want to add values.
Here's what the syntax of this statement looks like:
You might have correctly noticed that this is a snippet of the script from the previous chapter, where data is inserted into the library
table.
Let's break down what's happening here:
- First, the keywords
INSERT INTO
are written, followed by thetable_name
into which the data will be inserted; - Then, parentheses are opened, and the column names into which the data will be inserted are specified; in our case, there are 4 columns;
- After that, the keyword
VALUES
is written, and parentheses are opened where the data will be written; - The data should be written in the same order as the column names were specified, and the data types must be observed. You cannot insert an integer value into a column with the
VARCHAR
data type; - The parentheses are closed, and a comma is placed, thus filling one row. You can fill as many rows as you deem necessary using this method.
In summary, the generic syntax of the INSERT
statement looks like this:
Don't forget about the semicolon in the end!
Let's move on to the task!
Task
There is an empty table called employees
with the following columns:
Yes, it's the same table as in the previous sections, but now this table doesn't contain any data (rows) at all.
Your task is to:
- Add a column
country
to this table, which will contain information about the country where the employee resides; - Insert 2 rows of data into the table, which will look like this:
id=1, first_name=Emily, last_name=Torres, department=Operations, salary=80000, country=United Kingdom
;id=2, first_name=David, last_name=Bobr, department=Engineering, salary=95000, country=Poland
.
To accomplish this task, use ALTER TABLE
for the first subtask and INSERT
for the second subtask.
Note
On the right side of the code editor, some code will already be written. Please do not delete or edit this code, as it is necessary to check the correctness of your solution.
Also, don't forget to use semicolons after each part!