I have my below method which will accept two parameters-
final String userId- Primary Key for the database
final Collection<String> attributeNames- list of column names that I
want to retrieve
Below is the code
public Map<String, String> getAttributes(final String userId, final Collection<String> attributeNames) {
//Below line doesn't works out the way I wanted
String query="SELECT" +attributeNames.toString()+ ", * from test where id = "+userId+ ";";
ResultSet result = CassandraDatastaxConnection.getInstance().getSession().execute(query);
for (Row rows: result){
System.out.println(rows.getString("key"));
}
return attributes;
}
let's take an example, userId as 40
Sample attributeNames will look like this-
[account, behavior, segmentation]
Now I need to generate a SQL corresponding to the inputs. So for above example, sql should look like this-
SELECT account, behavior, segmentation from test where id = "40";
How can I generate a SQL like this from the above inputs? Thanks for the help.
You can use something like attributeNames.toString().substring(1, attributeNames.toString().length()-1)
Change this function
public Map<String, String> getAttributes(final String userId, final Collection<String> attributeNames) {
//Below line doesn't works out the way I wanted
String query="SELECT" +attributeNames.toString()+ ", * from test where id = "+userId+ ";";
ResultSet result = CassandraDatastaxConnection.getInstance().getSession().execute(query);
for (Row rows: result){
System.out.println(rows.getString("key"));
}
return attributes;
}
to this
public Map<String, String> getAttributes(final String userId, final Collection<String> attributeNames) {
//Below line doesn't works out the way I wanted
StringBuilder sb = new StringBuilder(attributeNames.size());
for(int i = 0; i<attributeNames.size();i++)
{
sb.append(attributeNames.get(i));
if(i != attributeNames.size() - 1)
sb.append(",");
}
String query="SELECT" +sb.toString()+ " from test where id = "+userId+ ";";
ResultSet result = CassandraDatastaxConnection.getInstance().getSession().execute(query);
for (Row rows: result){
System.out.println(rows.getString("key"));
}
return attributes;
}
The modified function runs a loop through the attribute names and constructs the query part as name1, name2, name3, etc and then adds it to the query body. Hope this solves your problem.
Related
I have my one table like UserTable.
#Entity
public class UserTable{
#PrimaryKey(autoGenerate = true)
private int userId;
private String userName;
private String userEmailId;
// Below code is getter and setter of this class.
}
#Dao
public interface UserDao {
#Query("SELECT * FROM userTable")
public List<UserTable> loadAllUsers();
#Insert
public long insertUserTable(UserTable userTable);
#Insert
public long[] insertUserTables(UserTable... userTables);
#Update
public int updateUserTable(UserTable userTable);
#Delete
public int deleteUserTable(UserTable userTable);
#RawQuery
public abstract List<UserTable> loadAllUserListByGivenIds
(SupportSQLiteQuery query);
public default List<UserTable> loadAllUserListByIds(long[] userIds) {
List<UserTable> list;
ArrayList<Object> argsList = new ArrayList<>();
String selectQuery = "SELECT * FROM UserTable WHERE userId IN (?);";
argsList.add(userIds);
SimpleSQLiteQuery simpleSQLiteQuery = new SimpleSQLiteQuery(selectQuery, argsList.toArray());
list = loadAllUserListByGivenIds(simpleSQLiteQuery);
return list;
}
}
// Now in My MainActivity.class file, I have use following code:
List<UserTable> userList= databaseClient
.getAppDatabase()
.userDao()
.loadAllUserListByIds(new long[]{1L,2L});
My query is running in normal database, but when I was pass array of user ids then, in #RawQuery() method of dao class is not supported for "IN" clause used in where condition "WHERE userId IN (?)".
How, I will use "IN" clause in #RawQuery() of room database.
Much easier to use an #Query it's as simple as:-
#Query("SELECT * FROM UserTable WHERE userId IN (:idList)")
public List<UserTable> getWhatever(long[] idList);
You'd then use getWhatever(new long[]{1L,2L})
If you need it an #rawQuery though you could do it like (used previous answer code for my convenience) :-
private List<TableXEntity> loadAllUserListByIds(int order,long[] idList) {
StringBuilder idListAsCSV = new StringBuilder(); //<<<<<<<<<<
boolean afterFirst = false; //<<<<<<<<<<
//<<<<<<<<<< all of the loop to create the CSV
for (Long l: idList) {
if (afterFirst) {
idListAsCSV.append(",");
}
afterFirst = true;
idListAsCSV.append(String.valueOf(l));
}
StringBuilder sb = new StringBuilder("SELECT * FROM ").append(DBHelper.TableX.NAME);
sb.append(" WHERE " + DBHelper.TableX.COLUMN_ID + " IN(").append(idListAsCSV).append(") "); //<<<<<<<<<<
switch (order) {
case DBHelper.TableX.FIRSTNAME_DESCENDING:
sb.append(DBHelper.TableX.ORDER_BY_FIRSTNAME_DESC);
break;
case DBHelper.TableX.FIRSTNAME_ASCENDING:
sb.append(DBHelper.TableX.ORDER_BY_FIRSTNAME_ASC);
break;
case DBHelper.TableX.LASTNAME_DESCENDING:
sb.append(DBHelper.TableX.ORDER_BY_LASTNAME_DESC);
break;
case DBHelper.TableX.LASTNAME_ASCENDING:
sb.append(DBHelper.TableX.ORDER_BY_LASTNAME_ASC);
break;
default:
break;
}
sb.append(";");
return roomDao.rawq(new SimpleSQLiteQuery(sb.toString(),null));
}
i.e. provide a CSV (although I vaguely recall being able to pass an array)
To use bind arguments (the recommended way as binding arguments protects against SQL injection) then you need a ? for each value and a corresponding array of objects.
So for 3 id's you need IN(?,?,?) and the actual values, the bind arguments, in an Object[]. The following is an example that does this noting that it shows 2 ways of building the Object[] (the bind arguments/values):-
private List<TableXEntity> loadByidList(long[] idlist) {
List<Object> bindargs = new ArrayList<>(); // way 1
Object[] args4Bind = new Object[idlist.length]; // way 2
StringBuilder placeholders = new StringBuilder(); // for the ? placeholders
/* Build the sql before the place holders */
StringBuilder sql = new StringBuilder("SELECT * FROM ")
.append(DBHelper.TableX.NAME)
.append(" WHERE ")
.append(DBHelper.TableX.COLUMN_ID)
.append(" IN (");
boolean afterfirst = false;
int i = 0; /* using for each so have index counter (as opposed to for(int i=0 ....) */
for (long l: idlist) {
bindargs.add(l); // for way 1
args4Bind[i++] = String.valueOf(l); // for way 2
if (afterfirst) {
placeholders.append(",");
}
afterfirst = true;
placeholders.append("?");
}
/* finalise the SQL */
sql.append(placeholders.toString())
.append(");");
//return roomDao.rawq(new SimpleSQLiteQuery(sql.toString(),bindargs.toArray())); // way 1
return roomDao.rawq(new SimpleSQLiteQuery(sql.toString(),args4Bind)); // way 2
}
Please try this, here it has working!
Try this simple trick to pass the arguments for IN operator-
List<Object> argList = new ArrayList<>();
argList.add("3");
argList.add("6");
Then prepare your raw query string:
Note- Match your argument list size with '?' size
String selectQuery = "SELECT * FROM task WHERE id IN (?,?)";
After this pass the raw query string to SimpleSQLiteQuery-
SimpleSQLiteQuery rawQuery = new SimpleSQLiteQuery(selectQuery, args.toArray());
Then fetch the List using DAO:
List<UserTable> taskList1=DatabaseClient
.getInstance(getApplicationContext())
.getAppDatabase()
.userTableDAO()
.getAllList(query);
We can do it in kotlin in the more simpler way.
Let's create two helper methos
object Helper {
fun sqlIn(list: List<Any>, bindArgs: MutableList<Any>): String {
bindArgs.apply { this.addAll(list) }
return "IN (${list.joinToString(",") { "?" }})"
}
fun sqlNotIn(list: List<Any>, bindArgs: MutableList<Any>): String = "NOT ${sqlIn(list, bindArgs)}"
}
Then you can use it in anywhere else
val ids = listOf(1, 2, 3)
val ownerId = 10
val bindArgs = mutableListOf<Any>()
val query = "SELECT * FROM posts WHERE id ${Helper.sqlIn(ids, bindArgs)} AND owner_id = ?"
bindArgs.add(ownerId)
dao.query(
SimpleSQLiteQuery(query, bindArgs.toTypedArray())
)
I have a nested SQL query to fetch employee details using their ID.
Right now I am using BeanListHandler to fetch data as a List<Details> but want to store it as a Map<String, Details> where the ID I originally pass needs to be the key for easy retrieval instead of searching the List with streams every time.
I have tried to convert to Maps but I am not sure of how to map the ID as String nor how to get the original ID passed to the inner Query as a column in the final result.
MainTest.java:
String candidateId = "('1111', '2222', '3333', '4444')";
String detailsQuery =
"select PARTNER, BIRTHDT, XSEXM, XSEXF from \"schema\".\"platform.view/table2\" where partner IN \r\n"
+ "(select SID from \"schema\".\"platform.view/table1\" where TYPE='BB' and CLASS='yy' and ID IN \r\n"
+ "(select SID from \"schema\".\"platform.view/table1\" where TYPE='AA' and CLASS='zz' and ID IN"
+ candidateId + "\r\n" + "))";
Map<String, Details> detailsView = queryRunner.query(conn, detailsQuery, new DetailsViewHandler());
Details.java:
public class Details {
private String candidateId;
private String birthDate;
private String maleSex;
private String femaleSex;
// getter and setter
}
DetailsViewHandler.java:
public class DetailsViewHandler extends BeanMapHandler<String, Details> {
public DetailsViewHandler() {
super(Details.class, new BasicRowProcessor(new BeanProcessor(getColumnsToFieldsMap())));
}
public static Map<String, String> getColumnsToFieldsMap() {
Map<String, String> columnsToFieldsMap = new HashMap<>();
columnsToFieldsMap.put("PARTNER", "candidateId");
columnsToFieldsMap.put("BIRTHDT", "birthDate");
columnsToFieldsMap.put("XSEXM", "maleSex");
columnsToFieldsMap.put("XSEXF", "femaleSex");
return columnsToFieldsMap;
}
}
Is there a way to get the ID (candidateId) in the result and what am I missing in terms of creating the key-value pairing ?
From the doc https://commons.apache.org/proper/commons-dbutils/apidocs/org/apache/commons/dbutils/handlers/BeanMapHandler.html
of constructor which you are using
public BeanMapHandler(Class<V> type,
RowProcessor convert)
// Creates a new instance of BeanMapHandler. The value of the first column of each row will be a key in the Map.
Above should work.
You can also try overriding createKey like so
protected K createKey(ResultSet rs)
throws SQLException {
return rs.getString("PARTNER"); // or getInt whatever suits
}
I'm working in Eclipse (Android). In the following blocks, EmployeeInt and RestaurantInt are data types and query() opens a connection to the database and parses the results. When I print the query results, I get identical strings, but the boolean is still false. I've tried trimming the strings, but that didn't help.
public boolean verifyEmployee(String email, String password) {
ArrayList<EmployeeInt> employeeEmailID = query("SELECT employeeID FROM employees WHERE emailAddress = \'"+email+"\'");
ArrayList<EmployeeInt> employeePasswordID = query("SELECT employeeID FROM employees WHERE password = \'"+password+"\'");
String stringEmployeeEmailID = employeeEmailID.toString();
String stringEmployeePasswordID = employeePasswordID.toString();
if(stringEmployeeEmailID.equals(stringEmployeePasswordID)) {
return true;
} else {
return false;
}
}
Executing the above gives me false, while executing the following block (virtually identical) gives me true.
public boolean verifyRestaurant(String email, String password) {
ArrayList<RestaurantInt> restaurantEmailID = query("SELECT restaurantID FROM restaurants WHERE emailAddress = \'"+email+"\'");
ArrayList<RestaurantInt> restaurantPasswordID = query("SELECT restaurantID FROM restaurants WHERE password = \'"+password+"\'");
String stringRestaurantEmailID = restaurantEmailID.toString();
String stringRestaurantPasswordID = restaurantPasswordID.toString();
if(stringRestaurantEmailID.equals(stringRestaurantPasswordID)) {
return true;
} else {
return false;
}
}
Can anyone point out my mistake?
EDIT
I changed it to this and it worked:
public boolean verifyEmployee(String email, String password) {
ArrayList<EmployeeInt> employeeEmailID = query("SELECT * FROM employees WHERE emailAddress = \'"+email+"\'");
ArrayList<EmployeeInt> employeePasswordID = query("SELECT * FROM employees WHERE password = \'"+password+"\'");
int intEmployeeEmailID = employeeEmailID.get(0).getID();
int intEmployeePasswordID = employeePasswordID.get(0).getID();
if(intEmployeeEmailID==intEmployeePasswordID) {
return true;
} else {
return false;
}
}
I know I could also use return (condition), but I would like to add some messages if the login fails, something like:
System.err.println("email address and password do not correspond");
I'm not making an app to publish, it's merely for an assignment. Thanks for the help!
You are calling toString() on an ArrayList. Two different ArrayList objects will return two different toString() strings. You probably meant to get the first element of the ArrayList, and convert THAT to a string.
Example
EmployeeInt is your custom object. In my example, I assume it has some int field that can be retreived with getID().
ArrayList<EmployeeInt> idList = query("SELECT employeeID FROM employees WHERE emailAddress = \'"+email+"\'");
int ID = idList.get(0).getID();
stringEmployeeEmailID = String.valueOf(ID);
This may be easier to read than code:
query() returns an ArrayList
We extract the first element of the ArrayList - this is the part you left out
We get the ID of that element
We convert it to a String
I need to add some or clauses to query. I need to do it in a loop.
StringTokenizer st = new StringTokenizer(symptoms, ",");
while(st.hasMoreTokens()){
qb.whereOr(Properties.Symptom.like("%" + st.nextToken() + "%"));
}
How I can add those or conditions properly, because this above is not working as expected. I want to add or for every symptom.
If you look at the documentation, you'll see that whereOr() takes an unbounded number of conditions. What you want to do is add them all at once in an array:
StringTokenizer st = new StringTokenizer(symptoms, ",");
ArrayList<WhereCondition> whereConditions = new ArrayList<WhereCondition>();
while(st.hasMoreTokens()){
whereConditions.add(Properties.Symptom.like("%" + st.nextToken() + "%"));
}
// Give the ArrayList an already allocated array to place its contents in.
WhereCondition[] conditionsArray = new WhereCondition[whereConditions.size()];
conditionsArray = whereConditions.toArray(conditionsArray);
qb.whereOr(conditionsArray);
It looks like the method call in the documentation takes two non-array WhereConditions and then an ellipsized argument, which accepts an array or an additional comma-separated list of objects. So you might have to do something like this to get it to work properly:
qb.whereOr(conditionsArray[0], conditionsArray[1], Arrays.copyOfRange(conditionsArray, 2, conditionsArray.length));
ADDENDUM: It looks like you're using APIs that don't match the documentation, possibly an older version of greenDAO. I wrote this solution based off the current documentation. I can't guarantee that it will work for you. I recommend updating if possible.
Try this:
StringTokenizer st = new StringTokenizer(symptoms, ",");
WhereCondition where = null;
while(st.hasMoreTokens()){
if (where != null) {
where = qb.or(where, Properties.Symptom.like("%" + st.nextToken() + "%"));
} else {
where = Properties.Symptom.like("%" + st.nextToken() + "%");
}
}
qb.where(where).list();
I had the same problem so I added my own method in an Util class to perform the same behavior when I have one or several WhereCondition in an array.
Here is my gateway method :
public static QueryBuilder whereOr(QueryBuilder queryBuilder, WhereCondition[] whereConditions){
if(whereConditions == null) return queryBuilder.where(null);
else if(whereConditions.length == 1) return queryBuilder.where(whereConditions[0]);
else return queryBuilder.whereOr(whereConditions[0], whereConditions[1], Arrays.copyOfRange(whereConditions, 2, whereConditions.length));
}
Use : Util.whereOr(queryBuilder, whereConditionsArray);
Default : Can't use the Builder Pattern from the QueryBuilder with this approach
(More later) Here, I share you some code which could spare you time when developping DAO methods.
public class QueryBuilderUtil {
public static final String EQ = "=?";
public static final String NOTEQ = "<>?";
public static final String LIKE = " LIKE ?";
public static final String GE = ">=?";
public static final String LE = "<=?";
public static final String GT = ">?";
public static final String LT = "<?";
public static QueryBuilder whereOrOnSamePropertyWithDifferentValues(QueryBuilder queryBuilder, Property property, String operation, String values, String separator) {
return whereOrOnSamePropertyWithDifferentValues(queryBuilder, property, operation, values.split(separator));
}
public static QueryBuilder whereOrOnSamePropertyWithDifferentValues(QueryBuilder queryBuilder, Property property, String operation, String[] values) {
WhereCondition[] whereConditions = new WhereCondition[values.length];
int i = 0;
for (String value : values) {
whereConditions[i++] = new WhereCondition.PropertyCondition(property, operation, value);
}
return whereOr(queryBuilder, whereConditions);
}
public static QueryBuilder whereOr(QueryBuilder queryBuilder, WhereCondition[] whereConditions) {
if (whereConditions == null) return queryBuilder.where(null);
else if (whereConditions.length == 1) return queryBuilder.where(whereConditions[0]);
else return queryBuilder.whereOr(whereConditions[0], whereConditions[1], Arrays.copyOfRange(whereConditions, 2, whereConditions.length));
}
}
With this class, you can perform a whereOr with the same property on multiples "values string" in one line. It was necessary to clean my code :). However you can only do simple operations like variables declared in the class.
Example :
public List<Block> loadAllByModId(String mods_id) {
synchronized (this) {
QueryBuilder<Block> queryBuilder = queryBuilder();
QueryBuilderUtil.whereOrOnSamePropertyWithDifferentValues(queryBuilder, Properties.ModId, QueryBuilderUtil.EQ, mods_id, ";");
query_list = queryBuilder.build();
}
Query<Block> query = query_list.forCurrentThread();
return query.list();
}
Hope it helps
I have executed a query using JDBC and traversing the resultset I have stored all fields in List in java.
List<String> dataList=new ArrayList<String>();
while(res.next())
{
dataList.add(res.getString(1));
dataList.add(res.getString(2));
dataList.add(res.getString(3));
dataList.add(res.getString(4));
dataList.add(res.getString(5));
dataList.add(res.getString(6));
dataList.add(res.getString(7));
}
Iterator<String> it= dataList.iterator();
As I have added directly into list so how can I get this 7 fields while traversing the iterator.
Means:
while(it.hasNext())
{
String f1=it.next();
}
Like wise everytime I want 7 fields at a time
and next 7, next 7....... so on
Using this while loop how can I get those 7 fields (one row in table having 7 field) at a time.
I get little bit confuse here. Please help me.
Thanks
What you want to do is actually create another object that stores all seven of the values.
Then create a list of these entries so that you can access one row at a time, which is what I think you are asking.
First create a class for the row.
private static class Entry {
String[] row;
public Entry ( ResultSet r ) {
row = new String [ 7 ];
for (int i = 1; i <= 7; i++) {
row[i] = r.getString(i);
}
}
}
Using that, you can then create a list of Entry objects.
List<Entry> entryList = new ArrayList <Entry> ();
while(res.next())
{
entryList.add ( new Entry ( res ) );
}
Then, you can go ahead and loop through entryList and get any specific entry you would want.
Of course, if you have specific values, it might be wise to create instance variables of type String for Entry rather than an array of Strings.
By that I mean you could do this:
private static class Entry {
String column1; // rather than name column1 use what the column semantically represents
String column2;
// ...
public Entry ( ResultSet r ) {
column1 = r.getString(1);
// ...
}
This way, you can also calls like r.getInt(i) for certain columns which have an different type other than String.
Good luck!
I think your List declaration should be
List<Any DAO Object> instead of List<String>
While fetching from resultset, create a DAO object, add all fetched data into that object and then add that object into the list.
Then you can iterate and get each DAO object at each iteration.
You can use DatabaseMetaData class,
private static final String DRIVER = "com.mysql.jdbc.Driver";
private static final String URL = "jdbc:mysql://localhost/testdb";
private static final String USERNAME = "root";
private static final String PASSWORD = "";
public static void main(String[] args) throws Exception {
Class.forName(DRIVER);
Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
DatabaseMetaData metadata = connection.getMetaData();
ResultSet resultSet = metadata.getColumns(null, null, "users", null);
while (resultSet.next()) {
String name = resultSet.getString("COLUMN_NAME");
String type = resultSet.getString("TYPE_NAME");
int size = resultSet.getInt("COLUMN_SIZE");
System.out.println("Column name: [" + name + "]; type: [" + type + "]; size: [" + size + "]");
}
connection.close();
}