sqlTuple

sqlTuple(colNames)

Generate metacode with a tuple expression. The elements of the tuple are specified by colNames. sqlTuple is usually used with sql and makeUnifiedCall to dynamically generate SQL statements.

colNames is a STRING scalar/vector indicating column names.

A CODE scalar.

In the following example, the parameter args of makeUnifiedCall is tuple metacode generated using sqlTuple, and func is a user-defined function. The result of makeUnifiedCall is passed as the parameter select of function sql to generate SQL metacode c.

// Create a user-defined function
f = def (x,y)->(x-y)/(x+y)

// Create a table for query
t = table(1.0 2.0 3.0 as qty1, 1.0 3.0 7.0 as qty2)

// Generate metacode for query
c = sql(select=makeUnifiedCall(f, sqlTuple(`qty1`qty2)), from=t)

// Execute the corresponding metacode
c.eval()