fixed int data type selection based on size

[rafiulgits]

Pull request title integer data type selection by sizing should be fixed

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Conventions

• [x] Do only one thing
• [x] Non breaking API changes
• [x] Tested

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Pull request reason Fix sql server integer type selection based on go lang int value memory size

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User Case Description

https://github.com/go-gorm/sqlserver/blob/3c1621020dc4503717a93f7e7b9eb38c623aaa12/sqlserver.go#L158

SQL Server datatype selection based on int value data size is not appropriate. Here is the condition

switch {
case field.Size < 16:
    sqlType = "smallint"
case field.Size < 31:
    sqlType = "int"
default:
    sqlType = "bigint"
}

Golang integers

• int8 : 1 byte or 8 bits
• int16: 2 bytes or 16 bits
• int32: 3 bytes or 32 bits

• int64 4 bytes or 64 bits`

  SQL Server integers equivalent

  • tinyint : int8
  • smallint : int16
  • int : int32
  • biging : int64

The condition should be

switch {
case field.Size < 16:
    sqlType = "tinyint"
case field.Size < 31:
    sqlType = "smallint"
case field.Size < 64:
    sqlType = "int"
default:
    sqlType = "bigint"
}

)

[jinzhu]

reverted, tinyint equals int8, but size 15 will choose tinyint which will overflow?

[rafiulgits]

but one more issue still happening,

when I define a model like this

ProductID       int       `gorm:"type:int;not null"`

sql server database migration make it bigint automatically.

Whereas for type:tinyint, type:smallint, type:bigint are working perfectly. Can you describe this?

[rafiulgits]

reverted, tinyint equals int8, but size 15 will choose tinyint which will overflow?

but size 15 will never come, golang will select 8bit, 16bit, 32bit or 64bit.

If I am wrong then please correct my view.

Thanks @jinzhu

[jinzhu]

You can set with gorm size tag

On Sun, Feb 20, 2022 at 12:43 PM Rafiul @.***> wrote:

reverted, tinyint equals int8, but size 15 will choose tinyint which will overflow?

but size 15 will never come, golang will select 8bit, 16bit, 32bit or 64bit

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Jinzhu github.com/jinzhu

[iTanken]

reverted, tinyint equals int8, but size 15 will choose tinyint which will overflow?

Could we prevent overflow by using different types based on whether field.DataType is schema.Int or schema.Uint, for example, in #129:

https://github.com/go-gorm/sqlserver/commit/e01b9fffad2c446d49b407ac52d9e05a420bc1aa#diff-d4f96c05ed87dd1db12826d078654e8cb281186d30b116ba5ced4832c414a234R190