SQL Server - Multiple Where condition

How and why to use multiple where condition in sqlserver ?
give example how to use 2 or 3 where condition ?

cmd = new SqlCommand("select sum(credit) AS total from creditadd where cid<=cid and where userid='" + TextBox1.Text + "' and username='" + TextBox2.Text + "'", con);
is this is corret syntax ?

Hi remove second where from the condition
also there is no relevance of cid<=cid condtion

Hi,

Yes you can use multiple where condition in single query.

SQL always allows us to combine two or more conditions by using the AND and OR or NOT operators. Any number of simple conditions can be present in a single SQL statement, to allow us to create complex WHERE clauses that allow us to control which rows are included in our query results.

following is syntax to execute an SQL SELECT query with multiple conditions in the WHERE clause:

SELECT column_list
FROM table_name
WHERE column_name condition {[AND|OR} column_name condition}
So your query is correct

Hi here is an example.

select *
from table1 t1
WHERE
EXISTS
(
 Select * --or 1. No difference.
 From CRM_VCM_CURRENT_LEAD_STATUS Ex
 Where Lead_Key = :_Lead_Key
-- correlation here
AND
t1.CM_PLAN_ID = Ex.CM_PLAN_ID AND t1.CM_PLAN_ID =  Ex.Individual_ID
)

If you have multiple rows in the correlation then a JOIN gives multiple rows in the output, so you'd need distinct. Which usually makes the EXISTS more efficient.

Note "SELECT" * with a JOIN would also include columns from the row limiting tables

Where keyword should be single and you can put multiple condition with same where keyword in query with the help of Operator 'AND' or 'OR'
so everything is correct just you remove 2nd where keyword from your query

cmd = new SqlCommand("select sum(credit) AS total from creditadd where cid<=cid and userid='" + TextBox1.Text + "' and username='" + TextBox2.Text + "'", con);