4

How can I check in Tarantool SQL if a table already exists?

Elena Shebunyaeva
  • 211
  • 1
  • 6

1 Answers1

4

Using only SQL facilities it can be done this way:

SELECT EXISTS (select true from "_space" where "name" = 'table_name')

For instance:

tarantool> SELECT EXISTS (select true from "_space" where "name" = 'T1')
---
- metadata:
  - name: EXISTS (select true from "_space" where "name" = 'T1')
    type: boolean
  rows:
  - [true]
...

tarantool> SELECT EXISTS (select true from "_space" where "name" = 'T')
---
- metadata:
  - name: EXISTS (select true from "_space" where "name" = 'T')
    type: boolean
  rows:
  - [false]
...

In Lua mode:

tarantool> box.space.T1 ~= nil
---
- true
...

tarantool> box.space.T ~= nil
---
- false
...
NikitaRock
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  • Comparing to `nil` is only necessary if you explicitly want a boolean type or want to specifically express then and there the intent of checking for existance. Otherwise you can just do `if box.space.T1 then print 'yes' else print 'no' end` or `print(box.space.T1 and 'yes' or 'no')` :D – DarkWiiPlayer Jul 23 '19 at 11:37