运行我的Java代码时，我遇到此错误->

Question

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

my code:

public static void loanenquiry(String ApplicationID,String LoanNumber,String RIMNumber,String custname,String fromdate,String todate) {
    String wherestring = "SELECT * FROM bf_loanmaster WHERE";       

    try {
        if(ApplicationID != null) {
            wherestring = wherestring + "ApplicationID ="+BillAction.StringtoInt(ApplicationID)+"";
        }

        if(LoanNumber != null ) {
            if(ApplicationID != null) {
                wherestring =  wherestring  +  "AND LoanNumber = "+BillAction.StringtoInt(LoanNumber)+" ";
            } else {
                wherestring =  wherestring  +  "LoanNumber = "+BillAction.StringtoInt(LoanNumber)+" ";
            }
        }

        if(RIMNumber != null ) {
            if(ApplicationID != null && LoanNumber != null) { 
                wherestring =  wherestring  + "AND AdvparyRIM = "+RIMNumber+" ";
            } else {
                wherestring =  wherestring  + "AdvparyRIM = "+RIMNumber+"";
            }
        }

        if(custname != null ){
            if(ApplicationID != null && LoanNumber != null && RIMNumber != null ) {
                wherestring =  wherestring  +  "AND custName = "+custname+"";
            } else {
                wherestring =  wherestring  +  "custName = "+custname+"";
            }
        }

        if(fromdate != null ) {
            if(ApplicationID != null && LoanNumber != null && RIMNumber != null && custname != null ) {
                wherestring =  wherestring  +  "AND ApplicationDt >= "+BillAction.StringtoDate(fromdate)+" ";
            } else {
                wherestring =  wherestring  +  "ApplicationDt = "+BillAction.StringtoDate(fromdate)+"";
            }
        }
        if(todate != null ) {
            if(ApplicationID != null && LoanNumber != null && RIMNumber != null && custname != null && fromdate != null) {
                wherestring =  wherestring  +  "AND ApplicationDt >= "+BillAction.StringtoDate(fromdate)+" AND ApplicationDt <= "+BillAction.StringtoDate(todate)+"";
            } else {
                wherestring =  wherestring  +  "ApplicationDt >= "+BillAction.StringtoDate(todate)+"";
            }
        }

        Connection conn = BillFinanceDB.getDBConnection();
        PreparedStatement psloanenquiry= conn.prepareStatement(wherestring + ";");
        ResultSet rs =  psloanenquiry.executeQuery();

        while(rs.next()) {
            System.out.println("loan number"+rs.getInt("LoanNumber"));
        }
    } catch(SQLException e) {
        e.printStackTrace();
    }
}

Any ideas?

thanks for the help.

Answer 1

My guess: you're missing a space after WHERE in your constructed string. Try this:

String wherestring = "SELECT * FROM bf_loanmaster WHERE "; 

The best way to debug these kinds of errors is to print out the SQL query you have constructed before it is executed so that you can manually inspect it for problems.

Answer 2

The WHERE is most likely a problem. The second problem that you could have is not putting your strings in quotation marks. For example it probably should be wherestring = wherestring + "custName = '"+custname+"' ";

Also things to note:

All this appending is terribly inefficient, use a StringBuilder or StringBuffer instead. You could also use PreparedStatements which would make your code perform better and possibly even make it easier to read.

Answer 3

在位置之后添加空格。

Answer 4

give a space in your query

String wherestring = "SELECT * FROM bf_loanmaster WHERE";

there is no space between WHERE statement and condition.