| Re: [dtp-dev] Documents folders for DTP projects- SQL Query Parser user doc |
Hi,
Here is the user documentation on the SQL Query Parser. This needs to be enhanced further, but is good to get started when using the parser.
John:
Can you pls upload this to the website CVS?
(See attached file: SQL Query Parser User documentation.htm)
Rupesh Kartha,
Phone: 408 463 5804 T/L - 543 5804
Fax: 408 463 3834 T/L- 543 3834
Email: rkartha@xxxxxxxxxx
jograham@xxxxxxxxxx
Sent by: dtp-dev-bounces@xxxxxxxxxxx 12/20/2005 11:55 AM
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1. IntroductionThe SQL Query Parser (also referred to as ‘parser’ in this document) is a generated parser. LPG (Lexer Parser Generator) is used to generate the parser, which, based on a set of grammar rules, generates the Parser and Lexer source code in Java. The focus of this document is on how to use the generated parser. The parser takes SQL DML statements as input and creates instances of SQL Query Model classes if the SQL is syntactically valid. In addition to the syntactic validation, the parser can also perform a semantic validation. The parser is extensible to support vendor specific dialects and custom source generation. 2. Usage// imports needed import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.eclipse.datatools.modelbase.sql.datatypes.DataType; import org.eclipse.datatools.modelbase.sql.query.QueryStatement; import org.eclipse.datatools.modelbase.sql.query.ValueExpressionColumn; import org.eclipse.datatools.modelbase.sql.query.helper.StatementHelper; import org.eclipse.datatools.modelbase.sql.query.util.SQLQuerySourceFormat; import org.eclipse.datatools.modelbase.sql.schema.Database; import org.eclipse.datatools.sqltools.parsers.sql.SQLParseErrorInfo; import org.eclipse.datatools.sqltools.parsers.sql.SQLParserException; import org.eclipse.datatools.sqltools.parsers.sql.SQLParserInternalException; import org.eclipse.datatools.sqltools.parsers.sql.postparse.PostParseProcessor; import org.eclipse.datatools.sqltools.parsers.sql.query.SQLQueryParseResult; import org.eclipse.datatools.sqltools.parsers.sql.query.SQLQueryParserManager; import org.eclipse.datatools.sqltools.parsers.sql.query.SQLQueryParserManagerProvider; import org.eclipse.datatools.sqltools.parsers.sql.query.postparse.DataTypeResolver; import org.eclipse.datatools.sqltools.parsers.sql.query.postparse.TableReferenceResolver; 2.1
Invoking the parser
This code snippet below shows how to use the parser without using the semantic validation (known as post parse processing) and source formatting. try { // Create an instance the Parser Manager // SQLQueryParserManagerProvider.getInstance().getParserManager // returns the best compliant SQLQueryParserManager // supporting the SQL dialect of the database described by the given // database product information. In the code below null is passed for both the database and version // in which case a generic parser is returned SQLQueryParserManager parserManager = SQLQueryParserManagerProvider .getInstance().getParserManager(null, null); //Sample query String sql = "SELECT * FROM TABLE1"; //Parse SQLQueryParseResult parseResult = parserManager.parseQuery(sql); // Get the Query Model object from the result QueryStatement resultObject = parseResult.getQueryStatement(); // Get the SQL text String parsedSQL = resultObject.getSQL(); System.out.println(parsedSQL); } catch (SQLParserException spe) { // handle the syntax error System.out.println(spe.getMessage()); List syntacticErrors = spe.getErrorInfoList(); Iterator itr = syntacticErrors.iterator(); while (itr.hasNext()) { SQLParseErrorInfo errorInfo = (SQLParseErrorInfo) itr.next(); // Example usage of the SQLParseErrorInfo object // the error message String errorMessage = errorInfo.getParserErrorMessage(); // the line numbers of error int errorLine = errorInfo.getLineNumberStart(); int errorColumn = errorInfo.getColumnNumberStart(); } } catch (SQLParserInternalException spie) { // handle the exception System.out.println(spie.getMessage()); } 2.2
Getting a parser manager for a specific vendor
The recommended way is to instantiate a parser based on the database vendor information so as to handle vendor specific variations of SQL. The following code snippet shows how to create the parser based on the vendor information // TODO initialize the variable db with the // org.eclipse.wst.rdb.internal.models.sql.schema.Database intance obtained from // the database connection // Database db; // TODO get the vendorname and version after the variable is initialized // String dbName = db.getVendor(); // String dbVersion = db.getVersion(); // get the best matching parser manager depending on what parser extension are plugged in SQLQueryParserManager parserManager = SQLQueryParserManagerProvider .getInstance().getParserManager(dbName, dbVersion); If not matching parser is found, then the generic parser is retuned. 2.3
Using post parse processing and source formatting
The semantic validation of the parsed
SQL is done in a step called the Post Parse Processing. At present there are two types of
semantic validations are supported.
Appending the schema name to the
database object (for example schema1.table1) is optional, when the parser
generates the SQL after a successful parse. The following code snippet shows how to
configure post parse processors and the source formatting for the parser. //
TODO initialize the variable db with the //
org.eclipse.wst.rdb.internal.models.sql.schema.Database intance obtained from //
the database connection //
initialize the variable currentSchemaName to be the schema name //
Database database; //
String currentSchemaName; //
String dbName = db.getVendor(); //
String dbVersion = db.getVersion(); String
sql = "SELECT * FROM TABLE1"; //
create the post parse processors, maybe wrapped in createPostParseProcessorList() PostParseProcessor tableRefResolver
= new TableReferenceResolver( database,
currentSchemaName); PostParseProcessor dataTypeResolver
= new DataTypeResolver(); //
ordering is important for post parse processing! first we need to fill //
in the database information for table references and column types List
postParseProcessors = new ArrayList(); postParseProcessors.add(0, tableRefResolver); postParseProcessors.add(1, dataTypeResolver); //
get the SQL source format options and set at least the current schema //
that is omited but implicit for any unqualified table
references //
important for later resolving of table references! SQLQuerySourceFormat sourceFormat
= SQLQuerySourceFormat .copyDefaultFormat(); sourceFormat.setOmitSchema(currentSchemaName); SQLQueryParserManager
parserManager = SQLQueryParserManagerProvider .getInstance().getParserManager(dbName,
dbVersion); parserManager.configParser(sourceFormat,
postParseProcessors); //
parse the SQL statement try
{ SQLQueryParseResult
parseResult = parserManager.parseQuery(sql); List
semanticErrors = parseResult.getErrorList(); Iterator
itr = semanticErrors.iterator(); while
(itr.hasNext()) { SQLParseErrorInfo
errorInfo = (SQLParseErrorInfo) itr.next(); //
the error message String
errorMessage = errorInfo.getParserErrorMessage(); //
the line numbers of error int
errorLine = errorInfo.getLineNumberStart(); int
errorColumn = errorInfo.getColumnNumberStart(); //
Error processing for specific errors String
errorCode = errorInfo.getErrorCode(); if
(TableReferenceResolver.ERROR_CODE_TABLE_UNRESOLVED .equals(errorCode)) { //
table not found }
else if (TableReferenceResolver.ERROR_CODE_COLUMN_UNRESOLVED .equals(errorCode) ||
TableReferenceResolver.ERROR_CODE_NONEXISTENT_COLUMN .equals(errorCode)) { //
column not found } } }
catch (SQLParserException spe) { //
handle the syntax exception System.out.println(spe.getMessage()); }
catch (SQLParserInternalException spie) { //
handle the exception System.out.println(spie.getMessage()); } 2.4
Getting result columns
// the effective result columns of a QuerySelectStatement are the columns that are returned by // the select statement // e.g.: SELECT SUBQRY.* FROM (SELECT COL1, COL2 FROM TABLEA) AS SUBQRY // QueryStatement queryStmt = parserManager.parseQuery("SELECT SUBQRY.* FROM (SELECT COL1, COL2 FROM TABLEA) AS SUBQRY"); // get the List of effective result columns with data types List columnExprList = StatementHelper .getEffectivesResultColumns(queryStmt); Iterator columnIt = columnExprList.iterator(); while (columnIt.hasNext()) { ValueExpressionColumn colExpr = (ValueExpressionColumn) columnIt .next(); DataType dataType = colExpr.getDataType(); System.out.println("effective result column: " + colExpr.getName() + " with data type: " + dataType.getPrimitiveType()); } // expected Output of example "SELECT SUBQRY.* FROM (SELECT COL1, COL2 FROM TABLEA) AS SUBQRY": // effective result column: COL1 with data type: VARCHAR // effective result column: COL2 with data type: VARCHAR } 3 Parser Plugins
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