bms

Does QueryToClass have numeric indexing?

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I have an issue querying a large database where some column names on separate tables are the same. In rare cases the query will include 2 or more of these datasets, and I therefore can't tell them apart using QueryToClass, as they have the same FieldName.

EG I have two tables in my database, one for GHI Irradiance, and the other for POA Irradiance. Both have a column name "Irradiance." If the user wishes to graph both against each other:

private RO = DB.QueryToClass(SQLTools.MySQLHandle, SQLQuery) 

RO.FieldNames // contains: {"Time_Stamp", "Irradiance", "Irradiance"}

GraphTrace1 = evaluate(format("RO.%s", RO.Fieldnames[1]))
GraphTrace2 = evaluate(format("RO.%s", RO.Fieldnames[2]))		//Ambigious, always uses data from the first RO.Irradiance

Is there a way to access the data some other way than via the FieldNames string array?

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The best way to do this is to use the AS SQL keyword to provide an alias for the desired tag.  For example:

select myField as myAlias from myTable;

This is actually the only way to do SQL function selects, for example:

select sum(myField) as theSum from myTable;

or more common:

select min(myTimeFIeld) as startTime from myTable;

Of course your SQL commands may differ slightly due to the varying dialects of SQL.

 

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