sqlTuple

sqlTuple(colNames)

colNames is a STRING scalar/vector indicating column names.

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.

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()