Learn salt DECODE() MySQL knowing the password ?

[HashMania]

MySQL DECODE() & ENCODE() => github source

ENCODE:

Code:

INSERT INTO users(pass) VALUES (ENCODE('pass123','salt'))

OUT:

Code:

q+ÀC[

DECODE:

Code:

SELECT DECODE(pass,'salt') as 'decode pass' FROM users

OUT:

Code:

pass123

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The database I have encrypted passwords, i know some of the passwords
Can I get salt with which passwords have been encrypted?
(to decrypt the remaining passwords)