sqlCol

sqlCol(colName, [func], [alias], [qualifier])

colName is a string scalar/vector indicating column name(s).

func (optional) is a unary function.

alias (optional) is a string scalar/vector indicating column name(s) of the selected column(s) or calculation result(s).

qualifier (optional) is a STRING scalar. It is only used in a table join operation when we need to select a column that appears in both tables and that is not a matching column. It indicates the table from which to select the column.

Generate metacode for selecting one or multiple columns with or without calculations. It is generally used together with function sql and eval to generate SQL statements dynamically.

t = table(`GME`AMC`KOSS as symbol, 325 13.26 64 as price);
colName="symbol";
sql(select=sqlCol(colName), from=t).eval();

colName="price";
sql(select=sqlCol(colName, max, `maxPrice), from=t).eval();

t1 = table(1 2 3 3 as id, 7.8 4.6 5.1 0.1 as value, 4 3 2 1 as x);
t2 = table(5 3 1 as id,  300 500 800 as qty, 44 66 88 as x) ;
sql(select=(sqlCol(`id),sqlCol(colName=`x, alias="t1_x", qualifier="t1"),sqlCol(colName=`x, alias="t2_x", qualifier=`t2)), from=<ej(t1,t2,`id)>).eval()