Question

In relation with this question about how to write long SQL queries within C#., the solution suggested that a long sql query should be written as:

string query = @"
    SELECT
        c.CUSTOMER_ID,
        COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME
        ct.NAME as CUSTOMER_TYPE
    FROM
        CT_CUSTOMER_TYPE AS ct INNER JOIN CUSTOMER AS c
            ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID
    "; 

That makes me curious about another related question. Can I use substitution somehow? That is, how would I manage if say the table name changes but the query remains the same? Do I have to fall back to using the other approach of building a string using string concatenations or is there a more elegant way?

Answer 1

Why not make use of string.Format? In the specific example you gave, you could do something like

string query = @"
SELECT
    c.CUSTOMER_ID,
    COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME
    ct.NAME as CUSTOMER_TYPE
FROM
    {0} AS ct INNER JOIN {1} AS c
        ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID
"; 

And the invoke

string real_query = string.Format(query, tblName1, tblName2);