How to get the first child value using dapper (typically querying count(*) as the only result)

Question

How to get the first child value using dapper (typically querying count(*) as the only result)

c# dapper orm sql

Question

I want to implement some function like this:

public static string GetResult(string sql) {
    // TODO: 
    // result = connection.Query(....);
    // return result.FirstRow().FirstChild().ToString();
}

And call like this:

string myName = GetResult("SELECT userName from tb_Users WHERE ID = 1");
// or
int totalRows = Convert.ToInt32(GetResult("SELECT count(*) FROM tb_List"));

How can I implement TODO section using Dapper ?

ineztia

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Accepted Answer

Dapper has ExecuteScalar[<T>] which can be used if you are reading one column, one row, one grid. So:

var name = connection.ExecuteScalar<string>("select 'abc'");
int count = connection.ExecuteScalar<int>("select 123");

There is also Query{First|Single}[OrDefault][<T>] for all the usual "sort of one row, multiple columns" scenarios.

A word of caution on your API: anything that only accepts a string of sql (and no separate parameters) makes me very nervous that you are about to cause sql injection problems.

How to get the first child value using dapper (typically querying count(*) as the only result)

Question

Accepted Answer

Performance

Expression Evaluator