In my database there are 3 column which is Name, Age, Gender.
In the program, I only want to use 1 search button. When the button is clicked, the program determine which 3 of the textbox has input and search for the right data.
How do you work with the query? For example if Name and Gender has text, the query :
"Select * from table Where (Name = #name) AND (Gender = #gender)"
And when only name is entered, I only query for the name. Must I check textbox by textbox whether there is user input and then write multiple query for each of them? Or is there a better way to do this?
Edit (29/5/16) : I tried doing this another way like this
myCommand = New MySqlCommand("Select * from project_record Where
(FloatNo = #floatNo OR FloatNo = 'None') AND
(DevCompanyName = #devCompanyName OR DevCompanyName = 'None') AND
(DevType = #devType OR DevType = 'None') AND
(LotPt = #lotPt OR LotPt = 'None') AND
(Mukim = #mukim OR Mukim = 'None') AND
(Daerah = #daerah OR Daerah = 'None') AND
(Negeri = #negeri OR Negeri = 'None') AND
(TempReference = #tempRef OR TempReference = 'None')", sqlConn)
But as you can guess already it will not work efficiently as well because if I only enter input for DevType and leave other textboxes blank, the query will not pull up all the records for DevType only. It will just display as no records.
Select * from table
Where (Name = #name OR #name is Null)
AND (Gender = #gender OR #gender is Null)
...
it should be one query
Other answers have explained how to simplify the query. It is especially important to get rid of the ORs, since they inhibit any use of indexes.
Once you have the query build cleanly, you need to think about the dataset and decide which columns are usually used for filtering. Then make a few INDEXes for them. You won't be able to provide 'all' possible indexes, hence my admonition that you think about the dataset.
When building indexes, you can have single-column or multiple-column indexes. For your type of data, I would suggest starting with several 2-column indexes. Make sure each index starts with a different column.
For Where (Name = #name) AND (Gender = #gender), here are some notes:
INDEX(gender) is useless because of low 'cardinality';
INDEX(gender, name) might be useful, but the following would be better:
INDEX(name)
Things like name and DevCompanyName are virtually unique, so a 1-column index is probably good.
If you had gender and age, then INDEX(age, gender) might be useful.
MySQL will almost never use two indexes for a single SELECT.
By the way, the construction of the WHERE could be done in a Stored Procedure. You would need CONCAT, PREPARE, etc.
Original answer
(scroll down to see update)
Can you try the following:
build a list only including values of the textboxes that have an input
set a string of the join the items of that list together with the " AND " string
append that string to your standard SELECT statement
The code looks like this:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim Predicate1 As String = Me.TextBox1.Text
Dim Predicate2 As String = Me.TextBox2.Text
Dim Predicate3 As String = Me.TextBox3.Text
Dim PredicateList As New List(Of String)
Dim WhereClause As String
Dim Query As String
If Predicate1 <> String.Empty Then
PredicateList.Add("Name=""" & Predicate1 & """")
End If
If Predicate2 <> String.Empty Then
PredicateList.Add("Age=""" & Predicate2 & """")
End If
If Predicate3 <> String.Empty Then
PredicateList.Add("Gender=""" & Predicate3 & """")
End If
WhereClause = String.Join(" AND ", PredicateList.ToArray)
Query = "SELECT * FROM TABLE WHERE " & WhereClause
MessageBox.Show(Query)
End Sub
Update
Further to the comments re SQL injection, here is an updated sample.
Dim Command As SqlClient.SqlCommand
Dim Predicate1 As String = Me.TextBox1.Text
Dim Predicate2 As String = Me.TextBox2.Text
Dim Predicate3 As String = Me.TextBox2.Text
Dim ParameterList As New List(Of SqlClient.SqlParameter)
Dim PredicateList As New List(Of String)
Dim BaseQuery As String = "SELECT * FROM TABLE WHERE "
If Predicate1 <> String.Empty Then
PredicateList.Add("name = #name")
ParameterList.Add(New SqlClient.SqlParameter("#name", Predicate1))
End If
If Predicate2 <> String.Empty Then
PredicateList.Add("age = #age")
ParameterList.Add(New SqlClient.SqlParameter("#age", Predicate2))
End If
If Predicate3 <> String.Empty Then
PredicateList.Add("gender = #gender")
ParameterList.Add(New SqlClient.SqlParameter("#gender", Predicate3))
End If
Command = New SqlClient.SqlCommand(BaseQuery & String.Join(" AND ", PredicateList.ToArray))
Command.Parameters.AddRange(ParameterList.ToArray)
COALESCE is your friend here. You can use it to make the where clause ignore comparisons where the parameter is NULL.
Select * from table Where (Name = COALESCE(#name,table.Name))
AND (Gender = COALESCE(#gender,table.Gender))
So, if the #name parameter is NULL, COALESCE(#name,table.Name) will return the value of the 'Name' column of the current row and (Name = COALESCE(#name,table.Name)) will always be true.
This assumes that if no value is entered in a textbox the corresponding parameter will be NULL. If instead it is a value such as 'None', you can use the NULLIF function to map 'None' to NULL
Select * from table Where
(Name = COALESCE( NULLIF( #name, 'None'), table.Name))
AND (Gender = COALESCE( NULLIF( #gender, 'None'), table.Gender))
How to implement a more efficient search?
The answer partly depends on what your definition of efficient is. I suspect you mean less code and fewer if blocks etc. But fundamentally, running a new SELECT * query to apply a filter is inefficient because your base data set can be all the rows and you just fiddle with the users View of it.
I have a DB with random data in columns for Fish, Color (string), Bird, Group (int) and Active which should be similar enough for Name, Age and Gender in the question - or that other long thing at the bottom.
DataTable
Fill a datatable and bind it to a DGV:
' form level object
Private dtSample As DataTable
...
' elsewhere
Dim sql = "SELECT Id, Name, Descr, `Group`, Fish, Bird, Color, Active FROM Sample"
Using dbcon As MySqlConnection = New MySqlConnection(MySQLConnStr)
' create SELECT command with the Query and conn
Dim cmd As New MySqlCommand(sql, dbcon)
...
daSample.Fill(dtSample)
daSample.FillSchema(dtSimple, SchemaType.Source)
End Using
dgv2.DataSource = dtSample
Going forward, we can filter the user's view of that table without issuing a new query.
Filter Controls
If some of the fields are limited to certain selections, for instance Gender, you can use a ComboBox instead of a TextBox. This is to help the user succeed and avoid typos (Make or Mael instead of Male; or here, correctly spelling Baracuda I mean Baraccuda, er Barracuda correctly.
For illustration purposes, Fish is something where the user can type in anything at all, but Bird is constrained to a set of choices. If there is a Bird table, cboBird can be bound or populated from it. But you may also be able to populate it from the master/base table:
Dim birds = dtSample.AsEnumerable.Where(Function(d) d.IsNull(5) = False).
Select(Function(d) d.Field(Of String)("Bird")).
Distinct.
ToArray()
cboBird.Items.AddRange(birds)
If "Finch" is a legal choice but there are none in the database, it wont show in the list. Depending on the app, this can be a Good Thing:
If the user filters on Finch and there a no resulting records, you won't need a MessageBox or StatusBar message explaining the empty result set.
If something is not in the list, you are signalling up front that there are none of those. It then becomes a matter of training why a known element isnt in the list.
On the other hand, you'd have to repopulate those filter controls each time before they are used in case new records were added recently. If the controls are on a Dialog or different TabPage, this is easy to do as needed.
It isnt always applicable, but it can help the user avoid typos.
It depends on the app whether either method is of value.
DBNull / 'none'
I am not sure why you are adding 'none' to each clause. If someone want to see all the 'John` or all the 'Cod' records, it doesn't seem like they would also be interested in 'none'. Personally, Null/DBNull seems a better way to handle this, but it is easy to add or not add either form.
It would seem more valuable to filter to just those with DBNull/None. The code above for the Bird List filters out DBNull and I would do so for none as well. Then, before the result is added to the ComboBox, add a `None' item first so it is at the top.
Again it depends on what the app does; Or = 'None', may make perfect sense in this case.
Filter
Using a TextBox for Fish and Group, a ComboBox for Bird and Color and a CheckBox for Active, the code can form the filter thusly:
Dim filterTerms As New List(Of String)
Dim filterFmt = "{0} = '{1}' "
' OR:
' Dim filterFmt = "{0} = '{1}' OR {0} Is Null"
' OR:
' Dim filterFmt = "{0} = '{1}' OR {0} = 'none'"
If String.IsNullOrEmpty(tbSearchFish.Text) = False Then
Dim txt = tbSearchFish.Text.Replace("'", "''")
filterTerms.Add(String.Format(filterFmt, "Fish", txt))
End If
If cboBird.SelectedIndex > -1 Then
filterTerms.Add(String.Format(filterFmt, "Bird", cboBird.SelectedItem.ToString))
End If
If String.IsNullOrEmpty(tbGroup.Text) = False Then
Dim n As Int32
If Int32.TryParse(tbGroup.Text, n) Then
filterTerms.Add(String.Format(filterFmt, "[Group]", n))
End If
End If
If cboColor.SelectedIndex > -1 Then
filterTerms.Add(String.Format(filterFmt, "Color", cboColor.SelectedItem.ToString))
End If
If chkActive.Checked Then
' NOTE: I do not have TreatTinyAsBoolean turned on
' for some reason
filterTerms.Add(String.Format(filterFmt, "Active", "1"))
End If
If filterTerms.Count > 0 Then
Dim filter = String.Join(" AND ", filterTerms)
dtSample.DefaultView.RowFilter = filter
Dim rows = dtSample.DefaultView.Count
End If
Use whichever filterFmt is appropriate for what the app needs to do
A filter term is only added to the list if the related control has a value (as per above, this could include a 'None').
For the TextBox, it escapes any embedded ticks such as might be found in names like O'Malley or D'Artgnan. It replaces one tick with two.
Since Group is a numeric, a valid Int32 input is tested
If there are elements in the filterTerms list, a filter string is created
The filter is applied to the DefaultView.Filter (you can use also use a DataView or a BindingSource) so that the code need not query the database to provide filter capabilities.
Rows will tell you how many rows are in the current View.
The only halfway tricky one is a Boolean like Gender or Active because those actually resolve to three choices: {Any/Either, A, B}. For that, I would use a ComboBox and ignore it for SelectedIndex 0 as well. I didn't bother with this because the Combo concept is amply covered. Result:
Is it More "Efficient"?
It still depends.
It doesn't re-query the database to get rows the app can already have.
No new DBConnection, DBCommand or other DBProvider objects are created, just a list.
No need to dynamically create a SQL statement with N parameters in a loop to avoid SQL injection/special words and chars.
It doesn't even query the database for the items for the filter terms. If there is a static list of them in the DB, they could be loaded once, the first time they use the filters.
It is easy to remove the filter, no need to query yet again without WHERE clauses.
A ComboBox where applicable helps the user find what they want and avoid typos.
Is the SQL "cleaner". more "efficient? The code doesn't really mess with new SQL, just some WHERE clauses.
Is there less code? I have no idea since we just see the result. It doesnt string me as a lot of code to do what it does.
In my database there are 3 column which is Name, Age, Gender. In the program, I only want to use 1 search button. When the button is clicked, the program determine which 3 of the textbox has input and search for the right data.
And when only name is entered, I only query for the name. Must I check textbox by textbox whether there is user input and then write multiple query for each of them? Or is there a better way to do this?
SELECT * FROM `table`
WHERE (`name` = #name AND `name` IS NOT NULL)
OR (`age` = #age AND (`age`>0 OR `age` IS NOT NULL))
OR (`gender` = #gender AND `gender` IS NOT NULL);
With the above query if all text boxes have value, the result will not be one record (as if you where using logical AND between fields). If you want only that record you will filter it server-side with php from the rest of the results.
You can check the results on your own in this Fiddle
EDIT
In order to solve the above inconvenience (not bringing easily single results when needed) i got a little help from this answer and re-wrote the above query as:
SELECT *, IF(`name`=#name, 10, 0) + IF(`age`=#age, 10, 0) + IF(`gender`=#gender, 10, 0) AS `weight`
FROM `table`
WHERE (`name` = #name AND `name` IS NOT NULL)
OR (`age` = #age AND (`age`>0 OR `age` IS NOT NULL))
OR (`gender` = #gender AND `gender` IS NOT NULL)
HAVING `weight`=30;
OR to still get all records with a weight on result
SELECT *, IF(`name`=#name, 10, 0) + IF(`age`=#age, 10, 0) + IF(`gender`=#gender, 10, 0) AS `weight`
FROM `table` WHERE (`name` = #name AND `name` IS NOT NULL)
OR (`age` = #age AND (`age`>0 OR `age` IS NOT NULL))
OR (`gender` = #gender AND `gender` IS NOT NULL)
ORDER BY `weight` DESC;
You were pretty close. Let's look at
(FloatNo = #floatNo OR FloatNo = 'None')
So you want the field either to be the given input or 'None'? But there are (supposedly) no records in your table with FloatNo 'None'. What you really want to do is find out whether the input is none (i.e. empty):
(FloatNo = #floatNo OR #floatNo = '')
And for the case the user types in a blank by mistake, you can ignore this, too:
(FloatNo = #floatNo OR TRIM(#floatNo) = '')
The whole thing:
myCommand = New MySqlCommand(
"Select * from project_record Where
(FloatNo = #floatNo OR TRIM(#floatNo) = '') AND
(DevCompanyName = #devCompanyName OR TRIM(#devCompanyName) = '') AND
(DevType = #devType OR TRIM(#devType) = '') AND
(LotPt = #lotPt OR TRIM(#lotPt) = '') AND
(Mukim = #mukim OR TRIM(#mukim) = '') AND
(Daerah = #daerah OR TRIM(#daerah) = '') AND
(Negeri = #negeri OR TRIM(#negeri) = '') AND
(TempReference = #tempRef OR TRIM(#tempRef) = '')", sqlConn)
What is wrong with your approach?
Just change
(FloatNo = #floatNo OR FloatNo = 'None')
to
(FloatNo = #floatNo OR FloatNo = '' or FloatNo IS NULL)
And do that for every criteria.
Your query will respect empty values and NULL values after that.
I'm having a problem in retrieving last record id from database. This code below, is the closer I can get. But still, it return record id, as 0; ,then when I execute again, it will return, record of previous execute, not the current one.
sql = "insert into program (prog_det,budget,prog_obj,outcome,target_group,awareness,engagement,issue,seq_no) value ('"&prog_title&"','"&prog_budget&"','"&prog_obj&"','"&prog_result&"','"&prog_target&"','"&prog_aware&"','"&prog_involment&"','"&prog_issues&"','99');"
sql2 = "select last_insert_id() as last_id"
set kpi_prog_conn=Server.CreateObject("ADODB.Connection")
set kpi_prog_rs=Server.CreateObject("ADODB.Recordset")
kpi_prog_conn.Open ObjConn
kpi_prog_conn.Execute(sql)
kpi_prog_conn.Open sql2,objConn,adLockPessimistic
response.write kpi_prog_rs("last_id")
Your penultimate line looks wrong
Try
kpi_prog_rs.Open sql2,kpi_prog_conn,adLockPessimistic
IS the ID you are trying to retrieve is the Primary key of the corresponding table? Try using Scope_Identity() instead of last_insert_id()
Query - SELECT SCOPE_IDENTITY() AS [LAST_IDENTITY]
It returns you the last inserted id into the table
I don't have mysql but try:
sql2 = "select last_insert_id() as last_id;"
sql = "insert into program (prog_det,budget,prog_obj,outcome,target_group,awareness,engagement,issue,seq_no) value ('"&prog_title&"','"&prog_budget&"','"&prog_obj&"','"&prog_result&"','"&prog_target&"','"&prog_aware&"','"&prog_involment&"','"&prog_issues&"','99');" & sql2
set kpi_prog_conn=Server.CreateObject("ADODB.Connection")
kpi_prog_conn.Open ObjConn
set kpi_prog_rs = kpi_prog_conn.Execute(sql)
anotherRecordset = kpi_prog_rs.NextRecordset
response.write anotherRecordset("last_id")
I am working with MS-Access and JSP. I want to know that how can we create table with autonumber field and with primary key.
query="Create Table Registration_A (Reg_No PRIMARY KEY AUTOINCREMENT,
FName varchar(2))";
But its giving syntax error. What's the correct syntax?
CREATE TABLE Registration_A (
Reg_No AUTOINCREMENT,
FName VARCHAR(2),
CONSTRAINT RegA_PK PRIMARY KEY(Reg_No))
You can use the COUNTER keyword to create an AutoNumber field using DDL. I just tested this in a Java console app and it worked for me under both the JDBC-ODBC Bridge and UCanAccess:
String query =
"CREATE TABLE Registration_A (" +
"Reg_No COUNTER PRIMARY KEY, " +
"FName VARCHAR(2))";
Statement stmt = con.createStatement();
stmt.executeUpdate(query);
Seven years later, I don't see how to do this in DAO in any of the answers above or anywhere else on any Stack Exchange site. So here is the method I've worked out. The following VBA code creates a table with an autonumber field as primary key, puts some arbitrary data in it, then opens the table to show the results. I've run this code successfully in Access 2007.
Sub Make_Table_With_Autonum_Using_DAO()
Dim oDB As DAO.Database: Set oDB = CurrentDb()
Dim oTable As DAO.TableDef, sObjTable As String: sObjTable = "table_name"
Dim oField As DAO.Field, oIndex As DAO.Index
Dim oRS As DAO.Recordset
Set oTable = oDB.CreateTableDef(sObjTable)
With oTable
Set oField = .CreateField("ID_Object", dbLong) ' Create ID field.
oField.Attributes = dbAutoIncrField ' Make it autoincrement.
.Fields.Append oField ' Add to table's Fields collection.
Set oIndex = .CreateIndex("Index_Object") ' Create index.
oIndex.Primary = True ' Make it a primary key.
Set oField = oIndex.CreateField("ID_Object") ' Make index field for ID field.
oIndex.Fields.Append oField ' Add it to index's Fields coll'n.
.Indexes.Append oIndex ' Add index to table's Indexes coll'n.
Set oIndex = Nothing ' Remove index from memory.
Set oField = Nothing ' Remove field from memory.
.Fields.Append .CreateField("field2", dbText) ' Create and add other fields to
.Fields.Append .CreateField("field3", dbInteger) ' table's Fields collection.
' etc.
End With
oDB.TableDefs.Append oTable ' Add table to database's TableDefs collection.
Set oTable = Nothing
Set oRS = oDB.OpenRecordset(sObjTable) ' Enter arbitrary data into table.
oRS.AddNew: oRS!Field2 = "text 1": oRS!field3 = 123: oRS.Update
oRS.AddNew: oRS!Field2 = "text 2": oRS!field3 = 456: oRS.Update
oRS.AddNew: oRS!Field2 = "text 3": oRS!field3 = 789: oRS.Update
oRS.Close
DoCmd.OpenTable (sObjTable)
oDB.Close
Set oRS = Nothing
Set oDB = Nothing
End Sub
The Microsoft documentation for the necessary VBA elements, in order of appearance in the code, is:
TableDef.CreateField method (DAO)
Field.Attributes property (DAO)
Fields.Append method (DAO)
TableDef.CreateIndex method (DAO)
Index.Primary property (DAO)
Index.CreateField method (DAO)
Indexes.Append method (DAO)
That documentation says everything that needs to be known, but doesn't put it all together to explain how to make the autonumber primary key. The following MS documentation (no longer available directly from MS) does explain how to make the autonumber field, but not how to make it the primary key.
Programmatically Add Counter Field to Table Using DAO
In the following post on a Microsoft community forum, the accepted answer by Andrey Artemyev explains the whole thing.
Create a new table with AutoNumber field with VBA
My code above is essentially the same as his in that answer, with some additional commentary to explain what's going on.
This example uses ADOX to create a access table with an autonumber primary key
ADOX.Catalog cat = new ADOX.Catalog();
ADOX.Table table = new ADOX.Table();
ADOX.Key tableKey = new Key();
ADOX.Column col = new Column();
String connString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=c:\test.accdb; Jet OLEDB:Database Password=";
cat.Create(ConnString);
// Define column with AutoIncrement features
col.Name = "ID";
col.Type = ADOX.DataTypeEnum.adInteger;
col.ParentCatalog = cat;
col.Properties["AutoIncrement"].Value = true;
table.Name = "Security";
table.Columns.Append(col); // default data type is text[255]
table.Columns.Append("Username", ADOX.DataTypeEnum.adVarWChar, 255);
table.Columns.Append("Password", ADOX.DataTypeEnum.adVarWChar, 255);
table.Columns.Append("Engineer", ADOX.DataTypeEnum.adBoolean);
table.Columns.Append("Default", ADOX.DataTypeEnum.adBoolean);
// Set ID as primary key
tableKey.Name = "Primary Key";
tableKey.Columns.Append("ID");
tableKey.Type = KeyTypeEnum.adKeyPrimary;
// Add table to database
cat.Tables.Append(table);
You need to mention the data type first, then the Primary Key.
query="Create Table Registration_A (Reg_No AUTOINCREMENT PRIMARY KEY, FName varchar(2))";
Try this On
Create Table Registration_A
(
Reg_No AUTOINCREMENT,
FName varchar(2),
PRIMARY KEY(Reg_No)
);
CREATE TABLE `Tablename` (Field1 AUTOINCREMENT CONSTRAINT `Primarykey` PRIMARY
KEY, `Field2` DATETIME, `Field3` TEXT(25), `Field4` DOUBLE);
I have made database in SQL SERVER 2008 and have enabled the filestream technique. Now, how can I save the image to the SQL Server from vb 6.0. My database query for filesstream is as follows:
CREATE DATABASE Photo;
GO
ALTER DATABASE Photo
ADD FILEGROUP PhotoDBFS CONTAINS FILESTREAM;
GO
DECLARE #FilePath varchar(MAX) = (SELECT SUBSTRING(physical_name, 1, CHARINDEX(N'master.mdf', LOWER(physical_name)) - 1)
FROM master.sys.master_files
WHERE database_id = 1 AND file_id = 1) + 'PhotoDBFS_Filestream';
DECLARE #SQL varchar(MAX) = '
ALTER DATABASE Photo ADD FILE (
NAME = PhotoDBFSFile,
FILENAME = ''' + #FilePath + ''')
TO FILEGROUP PhotoDBFS;';
EXECUTE(#SQL);
GO
My table structure where I want to save the image is as follows:
CREATE TABLE Photos
(
PhotoId bigint NOT NULL PRIMARY KEY IDENTITY(1,1),
Title varchar(100) NOT NULL DEFAULT(''),
Subject varchar(100) NOT NULL DEFAULT('No Subject'),
Place varchar(100) NOT NULL DEFAULT('Unknown'),
Comment varchar(1000) NULL DEFAULT(''),
Rating tinyint NOT NULL DEFAULT(0),
PhotoFile varbinary(MAX) FILESTREAM NOT NULL,
CONSTRAINT PhotoRatingCheck CHECK(Rating >=0 AND Rating<=10)
);
My vb code for saving the image is as follows:
'Saving in the table [Photos]
Set Rs = New Recordset
SqlString = "SELECT * FROM Photos"
Rs.Open SqlString, con, adOpenStatic, adLockOptimistic, adCmdText
Rs.AddNew
Rs("UniqueId") = txtUniqueId.Text
Rs("CategoryId") = tempCategoryId
Rs("AlbumId") = tempAlbumId
Rs("Title") = txtTitle.Text
Rs("Subject") = txtSubject.Text
Rs("Place") = txtPlace.Text
Rs("Comment") = txtComment.Text
Rs("Rating") = sliderRating.Value
Rs("PhotoFile") = PhotoLocation
Rs.Close
Set Rs = Nothing
I get this error while saving.
Multiple-step OLE DB operation generated errors. check each OLE DB status value, if available. No work was done.
I also want to read the saved image from the database. Any suggestion???
You can't update IDENTITY columns, so remove assignment on UniqueId field, this fails now for certain.
When accessing the BLOB column PhotoFile sometimes helps to be explicit using Value property of the Field object i.e. Rs!PhotoFile.Value = binaryData or Rs("PhotoFile").Value = binaryData
For a table to have one or more FILESTREAM columns, it must also have a column of the uniqueidentifier data type that has the ROWGUIDCOL attribute. Does the CREATE TABLE statement you pasted in the question even work?