(" update payment set BATCHCODE=" + textBox2.Text + ", BATCHMEMBERS=" + comboBox6.Text + ", BATCHNAME='" + textBox10.Text + "', COURSE='" + comboBox5.Text + "', BRANCH='" + comboBox4.Text + "', COLLEGE='" + textBox8.Text + "', TITLE='" + textBox3.Text + "', TECHNOLOGY='" + comboBox2.Text + "', [TYPE]='" + comboBox1.Text + "',PROJECTSTATUS='" + comboBox3.Text + "',DELIVERYDATE='" + textBox9.Text + "', PROJECTCOST=" + textBox4.Text + ", PAIDAMOUNT=" + textBox12.Text + ",PAYMENT=" + textBox6.Text + ", BALANCE=" + textBox7.Text + " WHERE REGNO=" + textBox1.Text + "");
I mark my changes as a bold
also make sure that BATCHCODE , BATCHMEMBERS are not a string data type (i mean nvarchar,varchar etc....)