Android Tutorial DBUtils - Android databases are now simple!

Erel

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Latest version available here: https://www.b4x.com/android/forum/threads/b4x-dbutils-2.81280/

The DBUtils code module is designed to help you integrate SQLite databases in your program.
It contains a set of methods for common SQL tasks. Issues like escaping strings and identifiers are handled automatically.
The code module is included in the attached example project.
As of version 1.07, the following methods are included:

- CopyDBFromAssets: Copies a database file stored in the APK package (added in the Files tab) to a writable location. Only copies if the file doesn't yet exist.

- CreateTable: Creates a SQL table with the given fields and types. Also sets the primary key (optionally).

- DropTable: Deletes a table.

- InsertMaps: Efficiently inserts records to a table. The data is passed as a List that contains maps as items. Each map holds the fields and their values.
Example:
B4X:
    Dim ListOfMaps As List
    ListOfMaps.Initialize
    For i = 1 To 40
        Dim m As Map
        m.Initialize
        m.Put("Id", Id)
        m.Put("First Name", "John")
        m.Put("Last Name", "Smith" & i)
        ListOfMaps.Add(m)
    Next
    DBUtils.InsertMaps(SQL, "Students", ListOfMaps)
- UpdateRecord: Updates an existing record. Accepts the field name with the new value and a map of the 'where' fields.
Example:
B4X:
    Dim WhereFields As Map
    WhereFields.Initialize
    WhereFields.Put("id", "1234")
    WhereFields.Put("test", "test #5")
    DBUtils.UpdateRecord(SQL, "Grades", "Grade", 100, WhereFields)
- ExecuteMemoryTable: Executes a SELECT query and reads all the records into a list. Each item in the list is an array of strings that represents a record in the result set.

- ExecuteMap: Executes a SELECT query and returns the first record stored in a Map object. The columns names are the keys and the values are the map values.

- ExecuteSpinner: Executes a SELECT query and fills a Spinner view (ComboBox) with the values of the first column.

- ExecuteListView: Executes a SELECT query and fills the ListView with the values of the first column and optionally of the second column.

- ExecuteJSON: Executes a SELECT query and returns a Map which you can pass to JSONGenerator to generate JSON text.
Example:
B4X:
    Dim gen As JSONGenerator 'Requires a reference to the JSON library.
    gen.Initialize(DBUtils.ExecuteJSON(SQL, "SELECT Id, [Last Name], Birthday FROM Students", Null, _
        0, Array As String(DBUtils.DB_TEXT, DBUtils.DB_TEXT, DBUtils.DB_INTEGER)))
    Dim JSONString As String
    JSONString = gen.ToPrettyString(4)
    Msgbox(JSONString, "")
See the attached example and the DBUtils code module for more information about each method.

- ExecuteHtml: Creates a nice looking html table out of the results. You can show the results using WebView. This method is very useful both for development, as it allows you to see the data and also for reports.
You can change the table style by changing the CSS variable.
New: The last parameter defines whether the values will be clickable or not.
If the values are clickable then you should catch WebView_OverrideUrl event to find the clicked cell.


- GetDBVersion / SetDBVersion: Gets or sets the database version. The value is stored in a separate table named DBVersion. This is useful to manage updates of existing databases.
This feature was implemented by corwin42. Thank you!

About the example. In this example we are creating two tables: Students and Grades. The students table lists all the students.
The grades table lists the grade of each student in each test.

Uncomment ExportToJSON or ShowTableInWebView calls to see those features.





To hide the table, comment the call to ShowTableInWebView in Activity_Create.

Current version: 1.20
It depends on the following libraries: JSON, RuntimePermissions, SQL and StringUtils.

Make sure to add the following snippet to the manifest editor:
B4X:
AddManifestText(
<uses-permission
  android:name="android.permission.WRITE_EXTERNAL_STORAGE"
  android:maxSdkVersion="18" />
)
See RuntimePermissions tutorial for more information: https://www.b4x.com/android/forum/threads/runtime-permissions-android-6-0-permissions.67689/#content
 

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Last edited:

stevel05

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This will be extremely useful, Thanks Erel

Steve
 

JMB

Active Member
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I've ripped out about 30% of my rather inflexible code and replaced it with calls to DBUtils!

Absolutely superb. Thanks again. What a superb product this is!
 

Erel

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Using the new WebView_OverrideUrl event, the html table can now be made of clickable links instead of just text. This allows you to catch a cell selection event with the following code (included in the example):
B4X:
Sub WebView1_OverrideUrl (Url As String) As Boolean
    'parse the row and column numbers from the URL
    Dim values() As String
    values = Regex.Split("[.]", URL.SubString(7))
    Dim col, row As Int
    col = values(0)
    row = values(1)
    ToastMessageShow("User pressed on column: " & col & " and row: " & row, False)
    Return True 'Don't try to navigate to this URL
End Sub
The current CSS style makes the links look like regular text.

If you need the actual value you can first call ExecuteMemoryTable and then when the user clicks on a cell you can fetch the values from the memory table (list of arrays).
 

junaidahmed

Well-Known Member
Licensed User
WebView1_OverrideUrl is fine to get row and col number, but we would like to know how to get selected cell value.pls advise
 

Erel

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skizzo

Member
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To get the number of row and column is necessary that every element of the WebView has a link. In the function dbutils.ExecuteHtml it'is not expected. How can 'implement?
 

skizzo

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WebView2_OverrideUrl fails

Erel in the attached example, the event WebView2_OverrideUrl it's not executed. I can not understand what else is wrong.
 

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skizzo

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You have to cacth the OverrideUrl for example:

Sub WebView2_OverrideUrl (Url As String) As Boolean
Dim stringa_SQL As String
Dim SQL As SQL


'parse the row and column numbers from the URL
Dim values() As String
values = Regex.Split("[.]", URL.SubString(7))

Dim col, row As Int
col = values(0) ' this is the column selected
row = values(1) ' this is the row

stringa_SQL="SELECT id_cliente, id_giro, " _
& "seq, nome_cliente as cliente, " _
& "indirizzo, note " _
& "FROM ListaGiornata " _
& "ORDER BY seq DESC"

Dim riga() As String ' this is for storing the row selected
Lista = DBUtils.ExecuteMemoryTable(SQL, "" & stringa_SQL, Null, 0)
' lista now have the table value with in the first column the index
riga=Lista.Get(row)
main.IDRowSelected=riga(0) ' this is the index of the row selected in db

by
Steve (skizzo)
 
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