What is a database and Concatenation in SQL?

Concatenation or concat means to combine a string, text or data to gather and make one string in series without any middle variable”. Every language has its own operator for concatenation of multiple strings to gather. For example:

SQL provides a lot of ways to combine the string to gather. All methods are explaining below.

How to Concatenate in SQL?

We can use Build-in Functions and some special operator to concatenate the string in SQL.

Plus operator

In SQL “ + ” is very useful for concatenating two or more strings to gather. The syntax is given below,

SELECT String1 + ‘ ‘ + String2 AS label FROM Employees ;


SELECT ( LastName + ‘ , ‘ + FirstName ) AS Name 

FROM Person.Person 

ORDER BY LastName ASC , FirstName ASC ;

The CONCAT ( ) Function in SQL

CONCAT ( ) is built-in function for concatenating strings in SQL. We pass the two arguments in CONCAT ( ) function, the first one is string and second is number or string. The result will in the form on one string. Syntax of CONCAT ( ) function:

SELECT CONCAT ( ‘ Comments:  ‘ , 9 ) AS Result ;


Comments: 9

The CONCAT_WS ( ) Function in SQL

CONCAT_WS ( ) is also build-in function in SQL, it work like CONCAT ( ) function but in CONCAT_WS ( ) we passed three arguments. The first argument is the separator then string1 and string2.

SELECT CONCAT_WS ( ‘ :  ‘ , ‘ Comments ‘ ,  9 ) AS Result ;


Comments: 9

Example of Built-in Functions for Concatenating in SQL

The real use of CONCAT ( ) function in query is given below:


                               customer_id ,

                               first_name ,

                               last_name ,

                               CONCAT ( first_name , ‘ ‘ , last_name ) full_name




                               full_name ;

How to Concatenate in SQL Oracle

Oracle is a good Database management system, oracle also supports multiple ways to concatenate the strings. CONCAT ( ) is function is work similarly that already mentioned above. But also we can concatenate the string using “ || “ ( two pipes ) operator.

SELECT FirstName || ‘ ‘ || LastName AS FullName

FROM Employees

CONCAT ( ) Function:

SELECT CONCAT ( FirstName , ‘ ‘ , LastName ) AS FullName

FROM Employees

SQL Query Concatenation Example in C# Code

A real example of the concatenation of query in C# code:

using Microsoft.SqlServer.Server;

using System;

using System.Data.SqlTypes;

using System.IO;

using System.Text;

[SqlUserDefinedAggregate(Format.UserDefined, IsInvariantToDuplicates = false, IsInvariantToNulls = true, IsInvariantToOrder = false, MaxByteSize = 8000)]


public class Concatstr : IBinarySerialize {

    private StringBuilder result; 

    public void Init(){

        this.result = new StringBuilder();


    public void Accumulate(SqlChars value)


        if (value.IsNull || this.result.Length + value.Value.Length + 1 > 8000)




    public void Merge(Concatstr other)


        if (this.result.Length + other.result.Length > 8000)




    public SqlChars Terminate()


        string empty = string.Empty;

        if (this.result != null && this.result.Length > 0)

            empty = this.result.ToString(0, this.result.Length – 1);

        return new SqlChars((SqlString)empty);


    public void Read(BinaryReader r)


        this.result = new StringBuilder(r.ReadString());


    public void Write(BinaryWriter w)


        string str = this.result.ToString();

        if (str.Length >= 4001)

            str = str.Substring(0, 4001);




How do I concatenate two columns in SQL?

SELECT SOME_OTHER_COLUMN, CONCAT(FIRSTNAME, ‘,’, LASTNAME) AS FIRSTNAME FROM `customer`; Using * means, in your results you want all the columns of the table. In your case * will also include FIRSTNAME . You are then concatenating some columns and using alias of FIRSTNAME .

What is concatenation operator in SQL?

The concatenation operator is the plus sign (+). You can combine, or concatenate, two or more character strings into a single character string. You can also concatenate binary strings.

How do you concatenate a query?

To do this, open your query in design mode. Enter your field names in the query window separated by the & symbol. This query will return the concatenation of the FirstName field , a space character, and the [LastName] field. The results will be displayed in a column called Expr1.

How do I join 3 tables in SQL?

Inner Join with Three Tables
  1. Select table1.ID ,table1. Name.
  2. from Table1 inner join Table2 on Table1 .ID =Table2 .ID.
  3. inner join Table3 on table2.ID=Table3 .ID.

Can we Inner join three tables?

We‘ve used INNER JOIN 2 times in order to join 3 tables. This will result in returning only rows having pairs in another table. When you’re using only INNER JOINs to join multiple tables, the order of these tables in joins is not important.

How do I join 4 tables in SQL?

Joining 4 Tables in SQL Server Using Join
  1. From First Table i need to show emp_id, emp_name , emp_pf.
  2. from Second Table i need to show designation_name.
  3. from third Table i need to show pfacc1 and pfacc2.
  4. From Fourth Table i need to show pf_percent and pf_max.

How can I join more than two tables in SQL?

Joining More Than Two Tables

In SQL Server, you can join more than two tables in either of two ways: by using a nested JOIN , or by using a WHERE clause. Joins are always done pair-wise.

How do you join three tables?

We first join table 1 and table 2 which produce a temporary table with combined data from table1 and table2, which is then joined to table3. This formula can be extended to more than 3 tables to N tables, You just need to make sure that SQL query should have N-1 join statement in order to join N tables.

How do I join 4 tables inner join?

Introduction to PostgreSQL INNER JOIN clause
  1. First, specify columns from both tables that you want to select data in the SELECT clause.
  2. Second, specify the main table i.e., table A in the FROM clause.
  3. Third, specify the second table (table B ) in the INNER JOIN clause and provide a join condition after the ON keyword.

How do I join 3 tables inner join?

  1. SELECT column_name(s) FROM table1. INNER JOIN table2. ON table1.column_name = table2.column_name;
  2. Example. SELECT Orders.OrderID, Customers.CustomerName. FROM Orders. INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
  3. Example. SELECT Orders.OrderID, Customers.CustomerName, Shippers.ShipperName. FROM ((Orders.

Can we use two inner join in SQL?

Use an SQL INNER JOIN when you need to match rows from two tables. A common situation is where you need to join the primary key of one table to the foreign key of another. You need this when you are denormalizing data.

How can I retrieve data from 3 tables in SQL?

This statement is used to retrieve fields from multiple tables. To do so, we need to use join query to get data from multiple tables.

SQL SELECT from Multiple Tables

  1. SELECT orders. order_id, suppliers.name.
  2. FROM suppliers.
  3. INNER JOIN orders.
  4. ON suppliers. supplier_id = orders. supplier_id.
  5. ORDER BY order_id;

How do I select a column from 3 tables in SQL?


How many table we can join in SQL?

Theoretically, there is no upper limit on the number of tables that can be joined using a SELECT statement. (One join condition always combines two tables!) However, the Database Engine has an implementation restriction: the maximum number of tables that can be joined in a SELECT statement is 64.

How do you retrieve data from multiple tables in SQL without join?

You can wrap a query like this in a set of parenthesis, and use it as an inline view (or “derived table“, in MySQL lingo), so that you can perform aggregate operations on all of the rows. If your question was this — Select ename, dname FROM emp, dept without using joins..

How can I join two tables without joining?

Solution 1
  1. SELECT column1, column2, etc FROM table1 UNION SELECT column1, column2, etc FROM table2.
  2. SELECT table1.Column1, table2.Column1 FROM table1 CROSS JOIN table2 WHERE table.Column1 = ‘Some value’
  3. SELECT table1.Column1, table2.Column2 FROM table1 INNER JOIN table2 ON 1 = 1.

How do you join two tables with nothing in common?

One way to join two tables without a common column is to use an obsolete syntax for joining tables. With this syntax, we simply list the tables that we want to join in the FROM clause then use a WHERE clause to add joining conditions if necessary.