what’s the difference between a null value and an empty string in a table
tags: learning database diff-between
content
in a table, when we store a record, string for example, what’s the difference between null and ''
- database uses a flag to track which column is null
- the flag is just 1 bit in a null bitmap
- the flag is basically metadata for the column
- an empty string is still a string
- it’s a real string with length of 0
- the string still takes up space
- a null still takes space (metadata), but it takes very little space, it’s way more space efficient than empty string