function isValidInput(theForm) {
    var error_message = checkInput(theForm);
    if (error_message.match(/^This form|^Your query/)) {
        alert(error_message);
        return false;
    } else if (error_message != "") {
        flag = confirm(error_message);
        if (flag) {
            return true;
        } else {
            return false;
        }
    } else {
        return true;
    }
}

function checkInput(theForm) {
    var error_message = "";
    var b_input_condition = false;
    var search_item;
    var search_word;
    var MaxConditions = 5;
    var valid;
    for (var i = 1; i <= MaxConditions; i++) {
        search_item = getSelectedValue(theForm["item" + i]);
        search_word = theForm["search_word" + i].value;
        valid = checkText(search_word);
        if (valid == false) {
            error_message = "This form can be input alphanumeric characters, space and underscore.";
            break;
        }
        valid = checkWord(search_word);
        if (valid == false) {
            error_message = "Your query includes SQL command like word.";
            break;
        }
        if (search_word != "") {
            valid = checkLength(search_word);
            if (valid == false) {
                error_message = "Your query is too short. Plase input a string which contain more than two characters.";
                break;
            }
            b_input_condition = true;
        }
    }
    if (b_input_condition == false && error_message == "") {
        error_message = "Search conditions are not specified. Do you search all of data in CGED?";
    }
    return error_message;
}

function getSelectedValue(selObj) {
    return selObj[selObj.selectedIndex].value;
}

function checkText(search_word) {
    if (search_word.match(/[^a-z|A-Z|0-9|\_|\s+|\.]/)) {
        return false;
    }
}

function checkWord(search_word) {
    if (search_word.match(/(\s*select\s+)|(\s*insert\s+)|(\s*delete\s+)|(\s*update\s+)|(\s*create\s+)|(\s*drop\s+)|(\s+alter\s+)|(\s*rename\s+)/i)) {
        return false;
    }
}

function checkLength(search_word) {
    if (search_word.length < 2) {
        return false;
    }
}