## Syntax
```mermaid
%{init: {
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'themeVariables': {
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flowchart LR
Start((START)) --> LEVENSHTEIN_RATIO[LEVENSHTEIN_RATIO]:::quoted
LEVENSHTEIN_RATIO --> End((END))
```
## Purpose
The `LEVENSHTEIN_RATIO` SQL function says how much of two values is shared when they are read in order, on a scale from zero to one. It is one minus the distance which [[Invantive UniversalSQL/Grammar/SQL Functions/LEVENSHTEIN|LEVENSHTEIN]] reports, divided by the summed lengths of the two values. That distance counts a substitution as a deletion plus an insertion, so the ratio is the figure which is elsewhere called a sequence ratio.
Parameters:
- Text 1 (`varchar2`): the first value.
- Text 2 (`varchar2`): the second value.
Returns: the ratio as `double`, from zero to one. Returns `null` when one of the values is `null`.
## Examples
The following example compares two identical values:
```sql
select levenshtein_ratio('test', 'test')
-------------------
1
```
The following example compares two values which differ in one letter; the substitution costs two of the eight characters, so three quarters is shared:
```sql
select levenshtein_ratio('test', 'text')
-------------------
0,75
```
The following example compares two values which share no letter at all:
```sql
select levenshtein_ratio('abc', 'xyz')
-------------------
0
```