To write queries with concatenation and alias in Oracle, you can use the CONCAT function to combine different columns or strings together. This function takes two arguments and concatenates them into a single string.
You can also use the AS keyword to give an alias to the concatenated string or column in your query results. This alias provides a more readable name for the concatenated value in the output.
For example, you can write a query like this:
SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM employees;
This query will concatenate the first_name and last_name columns from the employees table with a space in between, and give the concatenated result the alias full_name in the query output.
By using concatenation and alias in Oracle queries, you can customize the output of your queries and make them more informative and user-friendly.
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How to assign aliases to columns in Oracle SQL queries?
In Oracle SQL queries, you can assign aliases to columns using the AS keyword followed by the desired alias name. Here is an example:
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SELECT column_name AS alias_name FROM table_name; |
In this query, column_name is the name of the column you want to give an alias, and alias_name is the alias you want to assign to it. You can also use the AS keyword optionally before the column name.
Here is an example query with aliases assigned to columns:
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SELECT first_name AS "First Name", last_name AS "Last Name" FROM employees; |
In this query, the columns first_name and last_name are given the aliases "First Name" and "Last Name" respectively. The aliases are enclosed in double quotes to allow for spaces and special characters in the alias names.
What is concatenation in Oracle SQL?
Concatenation in Oracle SQL refers to the process of combining two or more strings together. This is typically done using the concatenation operator "||". For example, "SELECT first_name || ' ' || last_name FROM employees" would combine the first name and last name of employees with a space between them.
How to concatenate strings with different lengths in Oracle SQL?
In Oracle SQL, you can concatenate strings of different lengths by using the CONCAT or || operator.
Here is an example using the CONCAT function:
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SELECT CONCAT('Hello, ', 'world!') AS concatenated_string FROM dual; |
And here is an example using the || operator:
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SELECT 'Hello, ' || 'world!' AS concatenated_string FROM dual; |
Both of these queries will result in the concatenated string "Hello, world!".
What is the limitation of using aliases in Oracle SQL queries?
One of the limitations of using aliases in Oracle SQL queries is that they cannot be used as identifiers in the ORDER BY clause. This means that you cannot sort the results of a query based on an alias. Additionally, aliases cannot be used in the WHERE clause, HAVING clause, or GROUP BY clause. This can make it more difficult to reference and manipulate the alias in the query.
