Database

SELECT * 
FROM MyTable
WHERE (telephone=@telephone AND @telephone IS NOT NULL)
OR ((family = @family AND name = @name) AND @telephone IS NULL)

string mySearch = "SELECT * "+
"FROM MyTable "+
"WHERE (telephone=@telephone AND @telephone IS NOT NULL) "+
"OR ((family = @family AND name = @name) AND @telephone IS NULL)";
SqlCommand cmd = SqlCommand(mySearch, myConnection);
cmd.Parameters.Add("@telephone", telephoneNumber);
cmd.Parameters.Add("@name", name);
cmd.Parameters.Add("@family", family);
SqlDataReader reader = cmd.ExecuteReader();
while(reader.Read())
{
    // Do what you need to do with each row from the table.
}

object telephoneNumber;
if (telephoneNumberTextBox.Text == "")
    telephoneNumber = System.DBNull.Value;
else
    telephoneNumber = telephoneNumberTextBox.Text;

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

'@myVar IS NULL' 

'@myVar'

'@'=variable in sql

// This is the text of the SQL Command.
// see that variable names start with the @ symbol
string mySearch = "SELECT * "+"FROM MyTable "+
    "WHERE (telephone=@telephone AND @telephone IS NOT NULL) "+
    "OR ((family = @family AND name = @name) AND @telephone IS NULL)";
SqlCommand cmd = SqlCommand(mySearch, myConnection);
 
// This adds the values to the SQL variables.
// These are called parameters.
cmd.Parameters.Add("@telephone", telephoneNumber);
cmd.Parameters.Add("@name", name);
cmd.Parameters.Add("@family", family);
 
// Run the SQL command and get the results.
SqlDataReader reader = cmd.ExecuteReader();
while(reader.Read())
{
    // Do what you need to do with each row from the table.
}

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

@telephone

-- First declare the variable
DECLARE @myIntegerVariable int
 
-- Now it can be used.
SET @myIntegerVariable = 12;

-- To get the result of a column in a SELECT statement that returns just one row. 
SELECT @myIntegerVariable = COUNT(*) FROM MyTable;
 
-- To use as a filter in a SELECT statement
SELECT * FROM MyTable WHERE MyColumn = @myIntergerVariable

CREATE PROCEDURE dbo.MyProc
@myFirstParameter int,
@mySecondParameter varchar(20)
AS
-- Do the processing of the Stored Procedure
GO

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

SELECT mineralID, SUM(value)
FROM MyTable
GROUP BY mineralID

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

<br />
CREATE VIEW vw_Mineral_total<br />
AS<br />
SELECT mineralID, SUM(value)<br />
FROM MyTable<br />
GROUP BY mineralID<br />

<br />
CREATE VIEW vw_Mineral_AVG<br />
AS<br />
SELECT mineralID, AVG(value)<br />
FROM MyTable<br />
GROUP BY mineralID<br />

btnOk_Click() Event