What is the string concatenation operator in Oracle?
It is ||, for example: select ‘Mr ‘ || ename from emp; The only “interesting” feature I can think of is that ‘x’ || null returns ‘x’, not null as you might perhaps expect.
plsql
What does it mean by select 1 from table?
select 1 from table will return the constant 1 for every row of the table. It’s useful when you want to cheaply determine if record matches your where clause and/or join.
What is the difference between SQL, PL-SQL and T-SQL?
SQL is a query language to operate on sets. It is more or less standardized, and used by almost all relational database management systems: SQL Server, Oracle, MySQL, PostgreSQL, DB2, Informix, etc. PL/SQL is a proprietary procedural language used by Oracle PL/pgSQL is a procedural language used by PostgreSQL TSQL is a proprietary procedural language … Read more
Is there a combination of “LIKE” and “IN” in SQL?
There is no combination of LIKE & IN in SQL, much less in TSQL (SQL Server) or PLSQL (Oracle). Part of the reason for that is because Full Text Search (FTS) is the recommended alternative. Both Oracle and SQL Server FTS implementations support the CONTAINS keyword, but the syntax is still slightly different: Oracle: WHERE … Read more