saving array itself in database.

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Hi,

I want to save array in database(mysql), My array contain 50 values e.g
a[0,1,0]= 2.3;
a[0,2,0]=8;
a[0,2,1]= 6;
.
.
.
a[0,50,1]=4.5

now I want to save this array in database, another way is to read value of each element of array and connate them to string and save in database but I do not want to do in that way. I directly want to save array in database as table tuple.

regards

Posted 1-Oct-13 22:49pm

rameshKumar1717

Updated 1-Oct-13 22:55pm

v5

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FoxRoot 2-Oct-13 4:58am

Use cascade iteration. For under for. And insert into the database every time in the related for scope.

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OriginalGriff · Accepted Answer · 2013-10-01T23:06:00

You can do it, just uses a VARBINARY format column in your database, and a BinaryFormatter in your C# code to convert the multidimensional array of doubles to a "flat" array of bytes:

C#

double[, ,] ar = new double[2, 3, 4];
ar[0, 1, 0] = 2.3;
ar[0, 2, 0] = 8;
ar[0, 2, 1] = 6;
...
ar[1, 2, 1] = 4.5;
// Convert to bytes
BinaryFormatter bf = new BinaryFormatter();
MemoryStream ms = new MemoryStream();
bf.Serialize(ms, ar);
byte[] data = ms.GetBuffer();
// Save bytes to DB

Then when you read them back as bytes:

C#

// Convert from bytes
BinaryFormatter bf = new BinaryFormatter();
MemoryStream ms = new MemoryStream(data);
double[, ,] ar2 = (double[,,])bf.Deserialize(ms);

Chris Ross 2 · Accepted Answer · 2013-10-01T23:13:00

I believe (but could be wrong) that 'tuple' in relational database terms means 'the group of columns that comprises a table', more or less.

On the basis of that definition, it would appear that you want to have a table with one column for each element in your array. Hopefully, I've misinterpreted you, because that is not a robust architecture ... when the array grows you'd need to add new columns (when, in a relational database, adding rows is the appropriate response, which is easy).

So, here's a solution that I think would work.

Your array is three dimensional, with each dimension being indexed by an int. The index set (tuple) that identifies a specific value in the array must be the Primary Key of the database table that holds the array values; the table will have one other column that contains the value, and may have others if you need to track when and by whom values were changed.

Here's a table definition that would accomplish this:

SQL

CREATE TABLE GiveMeAMeaningfulName
  (
  Index1 INT NOT NULL,             -- Give me a better name!
  Index2 INT NOT NULL,             -- And me!
  Index3 INT NOT NULL,             -- Me too
  Value FLOAT NOT NULL,            -- This column's name should probably relate to the table name; its type might be better as NUMERIC(xx,yy); if you were using a sparse array, it could be NULL, but you're not, so it is NOT NULL

  -- Optional change tracking
-- CreatedBy INT NOT NULL,  -- Data type as needed for your user table primary key
-- CreatedOn DATETIME NOT NULL,
-- AmendedBy INT NULL,
-- AmendedOn DATETIME NULL,

  -- Necessary primary key
  PRIMARY KEY (Index1, Index2, Index3)
  )
GO

Note - I work with Microsoft SqlServer; my SQL dialect may not work perfectly with MySql. The idea should nevertheless be valid.

With a table design like that you are free to save all elements of your array, or just those that have changed. As with all other times when a collection must be saved to / loaded from a database, unfortunately you have to iterate through the collection to save/load each element. There may be ways to do it with a single command that deals in bulk; if there are maybe others here will offer them (and I can learn, too!).

saving array itself in database.

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