plsql oracle check in constraint error

Assuming you are using a relatively recent version of Oracle, I'd use the new string escape syntax

EXECUTE IMMEDIATE q'[CREATE TABLE dependents    ( Id    NUMBER(6)    , FirstName     VARCHAR2(20)    , LastName      VARCHAR2(25)      CONSTRAINT    dep_last_name_nn  NOT NULL    , Birthdate Date    , Relation VARCHAR2(20)    , Gender char(1)     , RelativeId Number(6)     , CONSTRAINT pk_dependent primary key (Id)     , CONSTRAINT ck_gender CHECK(Gender in('F','M'))     )]';         

If you don't want to use the new syntax, you'll need two consecutive single quotes, not a double quote

EXECUTE IMMEDIATE 'CREATE TABLE dependents    ( Id    NUMBER(6)    , FirstName     VARCHAR2(20)    , LastName      VARCHAR2(25)      CONSTRAINT    dep_last_name_nn  NOT NULL    , Birthdate Date    , Relation VARCHAR2(20)    , Gender char(1)     , RelativeId Number(6)     , CONSTRAINT pk_dependent primary key (Id)     , CONSTRAINT ck_gender CHECK(Gender in(''F'',''M''))     )';         

I would, however, caution that dynamically creating objects is generally a bad idea-- there are generally better ways to accomplish this sort of thing.

The oracle engine expects 'F', 'M'. Since it is embedded in a string, you must use pascal-like escape for quotes, try this:

EXECUTE IMMEDIATE 'CREATE TABLE dependents    ( Id    NUMBER(6)    , FirstName     VARCHAR2(20)    , LastName      VARCHAR2(25)     CONSTRAINT     dep_last_name_nn  NOT NULL    , Birthdate Date    , Relation VARCHAR2(20)    , Gender char(1)     , RelativeId Number(6)     , CONSTRAINT pk_dependent primary key (Id)     , CONSTRAINT ck_gender CHECK(Gender in(''F'',''M''))     )';         

It will run as you want.

Change the CHECK constraint list to use single quotes:

CONSTRAINT ck_gender CHECK(Gender in(''F'',''M''))

Character constants in Oracle are enclosed in single quotes, not double quotes.