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Hello everybody! This is my first message to this list so I greed you
all! (I apologise in advance for my bad english). I am using HSQL in a VB.NET solution. At a certain point I want to parse an SQL SELECT query and draw a graph that visualizes the query in a very specific way. So I create a parser object (named p), and a select object (named sSelect) that the parser create when it calls the parseselect function. I know how to extract all the column and table names from the select object , but I cannot learn how to "read" the WHERE part of the SELECT statement. I have checked the code of the parser object, and I can understand that the WHERE part is stored in the eCondition _expression_. So my question is the following: How can I read the WHERE part of the SELECT statement and create a table for example that contains every condition that exists in the WHERE part? Now that I think about it a little more, how can I "read" all the expressions that exists in the eCondition _expression_? I tried using the SELECT.RESOLVE method and the PARSER.PARSEEXPRESSION method but I couldn't understand exactly how they work. Dim c As New SharpHSQL.Tokenizer(stSQL) 'stSQL is the SELECT statement that I want to parse Dim p As New SharpHSQL.Parser(d, c, channel) Dim sToken As String Dim sSelect As New SharpHSQL.Select sToken = c.getstring 'This is used just to remove the SELECT string sSelect = p.parseSelectAltered 'parseSelectAltered is a copy of the parseSelect method that is declared as PUBLIC Dim myLog As New Log("log.txt") 'PRINT TABLE AND COLUMN NAMES THAT EXISTS IN THE QUERY Dim ex As SharpHSQL._expression_ Dim myEnumerator As System.Collections.IEnumerator = sSelect.eColumn.GetEnumerator() myLog.Write("---==<{[ COLUMNS ]}>==---") myLog.Write("Alias" + ControlChars.Tab + "Tbl" + ControlChars.Tab + "Column" + ControlChars.Tab + "Type") While myEnumerator.MoveNext() ex = myEnumerator.Current myLog.Write(ex.getAlias + ControlChars.Tab + ex.getTableName + ControlChars.Tab + ex.getColumnName + ControlChars.Tab + Str(ex.getType)) End While myLog.Write("") myEnumerator = Nothing ex = Nothing Dim ta As TableFilter myEnumerator = sSelect.tFilter.GetEnumerator myLog.Write("---==<{[ TABLES ]}>==---") myLog.Write("Alias" + ControlChars.Tab + "Tbl") While myEnumerator.MoveNext() ta = myEnumerator.Current myLog.Write(ta.getName + ControlChars.Tab + ta.getTable.getName) End While myLog.Write("") myEnumerator = Nothing ta = Nothing |
