How to check whether column name exist while adding a new column.

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I wrote following sql query to add a column to a table.
but i want to find first whether any existing column has the same name which i dont know how to do.
I have put "comm.ExecuteNonQuery()" in Try-Catch statement- as it give exception when column name exist.
Am i doing it correct???

One more question : When writing following sql it creates column with data type:yes/No, this is what i want but it takes value 0/-1 but i have to check for true/false.

C#

ConnectionToDB();
string sql = "ALTER TABLE table_name ADD Proj bit";
comm.CommandType = CommandType.Text;
comm.CommandText = sql;
comm.Connection = conn;
conn.Open();
comm.ExecuteNonQuery();
conn.Close();

Thanks in advance

Posted 15-Sep-14 20:54pm

Member 11082315

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Thanks7872 16-Sep-14 3:11am

Altering table through code? Why?

4 solutions

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shijuse · Answer 1 · 2014-09-15T20:58:00

Solution 1

Hi
This link may be the solution for you

http://stackoverflow.com/questions/133031/how-to-check-if-column-exists-in-sql-server-table[^]

Posted 15-Sep-14 20:58pm

shijuse

Animesh Datta · Answer 2 · 2014-09-15T23:06:00

Solution 4

Hello Try this

If Not Exists(Select b.name from sysObjects a , syscolumns b 
where b.id = a.Id and a.Type ='U' and b.name = 'columnname' 
and a.name = 'tblname')
	Begin
		ALTER TABLE tblname ADD columnname INT 
	End
GO

thanks

Posted 15-Sep-14 23:06pm

Animesh Datta

Magic Wonder · Answer 3 · 2014-09-15T22:00:00

Solution 2

Hi,

Check this...Does a Database/Table/Column Exist in SQL Server[^]

But still....why do you want to perform it through code?

Hope this will help you

Cheers

Posted 15-Sep-14 22:00pm

Magic Wonder

Thomas Nielsen - getCore · Answer 4 · 2014-09-15T22:45:00

While you can make a coded part that work, i would recommend you consider what you want to do and then do it in another way than through code?

Anyway you can do like this

using System;
using System.Data;
using System.Data.SqlClient;

namespace Ramblings
{
    public class Inspector
    {
        public string ConnectionString;
        
        public void AddFieldToTable(string tableName, string columnName, string sqlType, bool nullable = true)
        {
            using (var cn = new SqlConnection(ConnectionString))
            {
                cn.Open();
                string SQL = "select top 1 * from " + tableName;
                using (var cmd = new SqlCommand(SQL, cn))
                {
                    SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.KeyInfo);
                    DataTable defTable = reader.GetSchemaTable();
                    if (defTable == null) throw new ArgumentException("No table returned for " + tableName, tableName);
                    reader.Close();
                    foreach (DataRow columnDescRow in defTable.Rows)
                    {
                        if (columnDescRow["ColumnName"].ToString() == columnName)
                        {
                            return;
                        }
                    }
                    SQL = "ALTER TABLE " + tableName + " ADD " + columnName + " " + sqlType + " " + (nullable ? "NULL" : "NOT NULL");
                    cmd.CommandText = SQL;
                    cmd.ExecuteNonQuery();
                }
            }
        }
    }
}