I have now facing the problem in bytea to Base64, actually I have save the image in below query,
user_profile_pic is defind in bytea in table
Update user_profile_pic
Set user_profile_pic = (profilepic::bytea)
Where userid = userid;
after that I have select the below query,
case 1:
SELECT user_profile_pic
FROM user_profile_pic;
its return exact same as I have updated, but after passing service its display a byte format
case 2:
Select encode(user_profile_pic::bytea, 'base64')
FROM user_profile_pic;
it returns totally different result.
I want to result case 1 along with service?
its working for me, not working query if write procedure/function, i write direct code behind
conn.Open();
NpgsqlCommand command = new NpgsqlCommand("SELECT profile_pic FROM userlog WHERE cust_id = '" + CustID + "'", conn);
Byte[] result = (Byte[])command.ExecuteScalar();
if(result.Length > 0)
{
ProfilePicture = Convert.ToBase64String(result);
ErrorNumber = 0;
ErrorMessage = "Successful operation";
}
else
{
ErrorNumber = 1;
}
conn.Close();
Related
I want to check the username and password with sqlite table,In my case query always returns false...
This is my Query...
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
if (c!=null)
{
return true;
}
else{
return false;
}
}
Checking whether or not the Cursor is null is basically useless as a valid Cursor will be returned by rawQuery. That is no data to extract will result in an empty Cursor with no rows, whilst if data has been extracted the Cursor will have 1 or more rows.
You should check whether or not the Cursor is empty by using the Cursor getCount() method which will return 0 if there are no rows or the number of rows. Alternately you could use some of the Cursor's move methods which will return true/false depending upon whether the move can be performed. e.g if (c.moveToFirst) { ... //row(s) exist} else { ... //no rows exists }.
You should also close the Cursor before returning. So perhaps use :-
public boolean validateUser(String u_name, String p_word){
Cursor c = getReadableDatabase().rawQuery(
"SELECT FNAME,PASSWORD FROM " + TABLE_NAME + " WHERE "
+ fname + "='" + u_name+"'AND "+ password +"='"+ p_word+"'" , null);
int count = c.getCount(); // get the number of rows
c.close(); // Close the Cursor
return count > 0; // return result (no data found = false, else true)
Many would recommend not using rawQuery but rather the convenience Cursor query method. This could be :-
public boolean validateUser(String u_name, String p_word) {
String[] columns = new String[]{
FNAME,
PASSWORD
};
String whereclause = FNAME + "=? AND " + PASSWORD + "=?";
String[] whereargs = new String[]{
u_name,
p_word
};
Cursor c = this.getWritableDatabase().query(
TABLE_NAME,
columns,
whereclause,
whereargs,
null,null,null
);
int count = c.getCount();
c.close();
return count > 0;
}
Note the above code is in-principle code and hasn't been tested so it may contain typing errors.
The above code assumes that the method is within the Database Helper class (i.e. a subclass of SQLiteOpenHelper).
The assumption has been made that FNAME and PASSWORD are the correct String variables to be used for the column names as opposed to fname and password
Assumptions have been made due to the limited code made available.
I am using Npgsql for postgresql in C++/CLI. So, the problem is, I have a db on my computer, and I am trying to select some of data from it's "movies" table. I already entered some data inside it, so I know that it has some data. But when I try to select some of them, answer to my query is empty. My code is like below:
public: string* SelectData(string* torrent)
{
conn->Open();
String ^ query = "SELECT title, director, actors, genre FROM movies";
Npgsql::NpgsqlCommand ^ command = gcnew NpgsqlCommand(query, conn);
try{
Npgsql::NpgsqlDataReader ^ dr = command->ExecuteReader();
for (int i = 0; i < N_TORRENT; i++)
{
if(dr->Read())
{
string std1 = toStandardString((String^)dr[0]);
string std2 = toStandardString((String^)dr[1]);
string std3 = toStandardString((String^)dr[2]);
string std4 = toStandardString((String^)dr[3]);
torrent[i] = std1 + " " + std2 + " " + std3 + " " + std4;
}
}
return torrent;
}
finally{
conn->Close();
}
}
(For the ones who will look for this question's answer)
Problem solved when I changed my query and look for the "title" column that are not empty. But this is ridiculus, so I beleive the problem was about pgAdmin. Because my insert query was not working either, but I added "rowseffected" variable and it shows the effected row's number and looks like it is working. So the problem is probably about the pgAdmin.
There is a procedure in %Dictionary.ClassDefinitionQuery which lists a class summary; in Java I call it like this:
public void readClasses(final Path dir)
throws SQLException
{
final String call
= "{ call %Dictionary.ClassDefinitionQuery_Summary() }";
try (
final CallableStatement statement = connection.prepareCall(call);
final ResultSet rs = statement.executeQuery();
) {
String className;
int count = 0;
while (rs.next()) {
// Skip if System is not 0
if (rs.getInt(5) != 0)
continue;
className = rs.getString(1);
// Also skip if the name starts with a %
if (className.charAt(0) == '%')
continue;
//System.out.println(className);
count++;
}
System.out.println("read: " + count);
}
}
In namespace SAMPLES this returns 491 rows.
I try and replicate it with a pure SQL query like this:
private void listClasses(final Path dir)
throws SQLException
{
final String query = "select id, super"
+ " from %Dictionary.ClassDefinition"
+ " where System = '0' and name not like '\\%%' escape '\\'";
try (
final PreparedStatement statement
= connection.prepareStatement(query);
final ResultSet rs = statement.executeQuery();
) {
int count = 0;
while (rs.next()) {
//System.out.println(rs.getString(1) + ';' + rs.getString(2));
count++;
}
System.out.println("list: " + count);
}
}
Yet when running the program I get this:
list: 555
read: 491
Why are the results different?
I have looked at the code of %Dictionary.ClassDefinitionQuery but I don't understand why it gives different results... All I know, if I store the names in sets and compare, is that:
nothing is missing from list that is in read;
most, but not all, classes returned by list which are not in read are CSP pages.
But that's it.
How I can I replicate the behaviour of the summary procedure in SQL?
Different is in one property. %Dictionary.ClassDefinitionQuery_Summary shows only classes with Deployed<>2. So, sql must be such.
select id,super from %Dictionary.ClassDefinition where deployed <> 2
But one more things is, why count may be different is, such sql requests may be compilled to temporary class, for example "%sqlcq.SAMPLES.cls22"
I have a simple function that just inserts the parameter values provided to it into columns in a table.
When I run the function via the ExecuteNonQuery() method on the command object I always get -1, even if the insert took place.
If i run the same query as a Text command it gives be the correct result of 1.
I'm new to postgresql/npgsql. Is there trick to making the function feed back the number of rows affected? Something like "set nocount off" in SQL Server?
EDIT:
The code I am using: (with npgsql 2.0.11)
var connStr = #"Server=127.0.0.1;Port=5432;User Id=postgres;Password=***;Database=Test;";
using (var conn = new NpgsqlConnection(connStr)) {
conn.Open();
using (var cmd = conn.CreateCommand())
{
cmd.CommandText = "insert_something";
cmd.CommandType = CommandType.StoredProcedure;
NpgsqlCommandBuilder.DeriveParameters(cmd);
cmd.Parameters["_id"].Value = 1;
cmd.Parameters["_val"].Value = 2;
var rowsAffected = cmd.ExecuteNonQuery();
Console.WriteLine(rowsAffected);
}
}
I haven't used Npgsql, but the documentation has an example with
the following code:
NpgsqlCommand command = new NpgsqlCommand("insert into table1 values(1, 1)", conn);
Int32 rowsaffected;
try
{
rowsaffected = command.ExecuteNonQuery();
}
If you are talking about some PostgreSQL function like this:
CREATE FUNCTION myinsert(integer) RETURNS void
LANGUAGE 'sql' AS 'INSERT INTO mytable VALUES ($1)';
and you are doing something like SELECT myinsert(1);, you can't get the number of affected rows, because you are running a SELECT and what the function does internally is opaque to you.
For ExecuteNonQuery() to get the number of rows affected, your postgresql function should return just that. An example would be:
CREATE OR REPLACE FUNCTION insert_something(_id int, _val int)
RETURNS int as $$
DECLARE count int;
BEGIN
INSERT INTO some_table (id, value) VALUES(_id, _val);
GET DIAGNOSTICS count = ROW_COUNT;
RETURN count;
END;
$$ language plpgsql;
Now if you call ExecuteNonQuery() from your code, you should get the inserted rows count.
Here's how I have implemented and its working for me without any issues:
Add an OUT Parameter to your function.
CREATE OR REPLACE FUNCTION schema.UpdateSomeValue(
IN par_updateId text,
OUT par_returnvalue INT4)
BEGIN
UPDATE schema.TableToUpdate
SET status = 1
WHERE ID = par_updateId;
GET DIAGNOSTICS par_returnvalue = ROW_COUNT;
END;
Now on the C# side
private int UpdateSomeValue()
{
var connStr = #"Server=127.0.0.1;Port=5432;UserId=postgres;Password=***;Database=Test;";
int result = -1;
using (var conn = new NpgsqlConnection(connStr)) {
conn.Open();
using (var cmd = conn.CreateCommand())
{
cmd.CommandText = "shema.UpdateSomeValue";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("par_updateId",NpgsqlTypes.NpgsqlDbType.INT, 1);
NpgsqlParameter outParm = new NpgsqlParameter("par_returnvalue",
NpgsqlTypes.NpgsqlDbType.Integer)
{
Direction = ParameterDirection.Output
};
cmd.ExecuteNonQuery();
result = Convert.ToInt32(outParm.Value);
}
}
return result;
}
PS : I tried the just ExecuteNonQuery() approach but it was always returning -1 for me (as if no rows has been affected NpgsqlDocumentation) Using above way I was able to capture the Number of rows affected from the PostgreSQL function and with OUT parameter it was easy to catch the affected rows on the client side.
I'm attempting to parse SQL using the TSql100Parser provided by microsoft. Right now I'm having a little trouble using it the way it seems to be intended to be used. Also, the lack of documentation doesn't help. (example: http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.tsql100parser.aspx )
When I run a simple SELECT statement through the parser it returns a collection of TSqlStatements which contains a SELECT statement.
Trouble is, the TSqlSelect statement doesn't contain attributes such as a WHERE clause, even though the clause is implemented as a class. http://msdn.microsoft.com/en-us/library/microsoft.data.schema.scriptdom.sql.whereclause.aspx
The parser does recognise the WHERE clause as such, looking at the token stream.
So, my question is, am I using the parser correctly? Right now the token stream seems to be the most useful feature of the parser...
My Test project:
public static void Main(string[] args)
{
var parser = new TSql100Parser(false);
IList<ParseError> Errors;
IScriptFragment result = parser.Parse(
new StringReader("Select col from T1 where 1 = 1 group by 1;" +
"select col2 from T2;" +
"select col1 from tbl1 where id in (select id from tbl);"),
out Errors);
var Script = result as TSqlScript;
foreach (var ts in Script.Batches)
{
Console.WriteLine("new batch");
foreach (var st in ts.Statements)
{
IterateStatement(st);
}
}
}
static void IterateStatement(TSqlStatement statement)
{
Console.WriteLine("New Statement");
if (statement is SelectStatement)
{
PrintStatement(sstmnt);
}
}
Yes, you are using the parser correctly.
As Damien_The_Unbeliever points out, within the SelectStatement there is a QueryExpression property which will be a QuerySpecification object for your third select statement (with the WHERE clause).
This represents the 'real' SELECT bit of the query (whereas the outer SelectStatement object you are looking at has just got the 'WITH' clause (for CTEs), 'FOR' clause (for XML), 'ORDER BY' and other bits)
The QuerySpecification object is the object with the FromClauses, WhereClause, GroupByClause etc.
So you can get to your WHERE Clause by using:
((QuerySpecification)((SelectStatement)statement).QueryExpression).WhereClause
which has a SearchCondition property etc. etc.
Quick glance around would indicate that it contains a QueryExpression, which could be a QuerySpecification, which does have the Where clause attached to it.
if someone lands here and wants to know how to get the whole elements of a select statement the following code explain that:
QuerySpecification spec = (QuerySpecification)(((SelectStatement)st).QueryExpression);
StringBuilder sb = new StringBuilder();
sb.AppendLine("Select Elements");
foreach (var elm in spec.SelectElements)
sb.Append(((Identifier)((Column)((SelectColumn)elm).Expression).Identifiers[0]).Value);
sb.AppendLine();
sb.AppendLine("From Elements");
foreach (var elm in spec.FromClauses)
sb.Append(((SchemaObjectTableSource)elm).SchemaObject.BaseIdentifier.Value);
sb.AppendLine();
sb.AppendLine("Where Elements");
BinaryExpression binaryexp = (BinaryExpression)spec.WhereClause.SearchCondition;
sb.Append("operator is " + binaryexp.BinaryExpressionType);
if (binaryexp.FirstExpression is Column)
sb.Append(" First exp is " + ((Identifier)((Column)binaryexp.FirstExpression).Identifiers[0]).Value);
if (binaryexp.SecondExpression is Literal)
sb.Append(" Second exp is " + ((Literal)binaryexp.SecondExpression).Value);
I had to split a SELECT statement into pieces. My goal was to COUNT how many record a query will return. My first solution was to build a sub query such as
SELECT COUNT(*) FROM (select id, name from T where cat='A' order by id) as QUERY
The problem was that in this case the order clause raises the error "The ORDER BY clause is not valid in views, inline functions, derived tables, sub-queries, and common table expressions, unless TOP or FOR XML is also specified"
So I built a parser that split a SELECT statment into fragments using the TSql100Parser class.
using Microsoft.Data.Schema.ScriptDom.Sql;
using Microsoft.Data.Schema.ScriptDom;
using System.IO;
...
public class SelectParser
{
public string Parse(string sqlSelect, out string fields, out string from, out string groupby, out string where, out string having, out string orderby)
{
TSql100Parser parser = new TSql100Parser(false);
TextReader rd = new StringReader(sqlSelect);
IList<ParseError> errors;
var fragments = parser.Parse(rd, out errors);
fields = string.Empty;
from = string.Empty;
groupby = string.Empty;
where = string.Empty;
orderby = string.Empty;
having = string.Empty;
if (errors.Count > 0)
{
var retMessage = string.Empty;
foreach (var error in errors)
{
retMessage += error.Identifier + " - " + error.Message + " - position: " + error.Offset + "; ";
}
return retMessage;
}
try
{
// Extract the query assuming it is a SelectStatement
var query = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).QueryExpression;
// Constructs the From clause with the optional joins
from = (query as QuerySpecification).FromClauses[0].GetString();
// Extract the where clause
where = (query as QuerySpecification).WhereClause.GetString();
// Get the field list
var fieldList = new List<string>();
foreach (var f in (query as QuerySpecification).SelectElements)
fieldList.Add((f as SelectColumn).GetString());
fields = string.Join(", ", fieldList.ToArray());
// Get The group by clause
groupby = (query as QuerySpecification).GroupByClause.GetString();
// Get the having clause of the query
having = (query as QuerySpecification).HavingClause.GetString();
// Get the order by clause
orderby = ((fragments as TSqlScript).Batches[0].Statements[0] as SelectStatement).OrderByClause.GetString();
}
catch (Exception ex)
{
return ex.ToString();
}
return string.Empty;
}
}
public static class Extension
{
/// <summary>
/// Get a string representing the SQL source fragment
/// </summary>
/// <param name="statement">The SQL Statement to get the string from, can be any derived class</param>
/// <returns>The SQL that represents the object</returns>
public static string GetString(this TSqlFragment statement)
{
string s = string.Empty;
if (statement == null) return string.Empty;
for (int i = statement.FirstTokenIndex; i <= statement.LastTokenIndex; i++)
{
s += statement.ScriptTokenStream[i].Text;
}
return s;
}
}
And to use this class simply:
string fields, from, groupby, where, having, orderby;
SelectParser selectParser = new SelectParser();
var retMessage = selectParser.Parse("SELECT * FROM T where cat='A' Order by Id desc",
out fields, out from, out groupby, out where, out having, out orderby);