Column Properties with the EMySQL API

Using the EMySQL API – Part 6

Foreword: In this part of the series, I talk about table column (field) properties obtained with the EMySQL API.

By: Chrysanthus Date Published: 28 Jul 2016

Introduction

This is part 6 of my series, Using the EMySQL API. In this part of the series, I talk about table column (field) properties obtained with the EMySQL API. You should have read the previous parts of the series before reaching here, as this is a continuation.

The EMysql package has an array of arrays. Each internal array represents a column. So, if there were six columns in the result set, there would be six internal arrays. Each cell of each internal array has a column property.

The values of the cells of each internal array are in the following order:

- Virtual Column Name
- Schema Name (database)
- Virtual Table Name
- Charset Number
- Column Width
- Field Type Number
- Field Type (meaning)
- MaximumShown Decimal Digits
- Default Value

As you can see, there are 9 properties.

Displaying Rows of the Array
For the pet table of the PetStore, the following code displays all the properties for the six columns:

    var selStr = `SELECT * FROM pet`;
    con.query(selStr, function(err, result, field)
        {
            if (err)
                console.log(err);
            else
                console.log(field);
        });

Note the use of the field argument in the definition of the callback function. I tried the code and I had:

[ [ 'name',
    'petstore',
    'pet',
    33,
    60,
    253,
    'MYSQL_TYPE_VAR_STRING',
    0,
    '' ],
  [ 'owner',
    'petstore',
    'pet',
    33,
    60,
    253,
    'MYSQL_TYPE_VAR_STRING',
    0,
    '' ],
  [ 'species',
    'petstore',
    'pet',
    33,
    60,
    253,
    'MYSQL_TYPE_VAR_STRING',
    0,
    '' ],
  [ 'sex', 'petstore', 'pet', 33, 3, 254, 'MYSQL_TYPE_STRING', 0, '' ],
  [ 'birth', 'petstore', 'pet', 63, 10, 10, 'MYSQL_TYPE_DATE', 0, '' ],
  [ 'death', 'petstore', 'pet', 63, 10, 10, 'MYSQL_TYPE_DATE', 0, '' ] ]

That is it for this part of the series. We stop here and continue in the next part.

Chrys

Broad Network

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