1Z0-149 study plan

Write and run inner-join queries across three tables using both ANSI JOIN ... ON syntax and the older comma-list WHERE style, then explain why the two produce identical result sets.

Distinguish inner joins from left, right, and full outer joins, and predict which rows survive each when the join column contains NULLs.

Construct self-joins against a single employee-style table to list each row alongside its parent row, and label the two table aliases clearly.

Write a SELECT statement that projects specific columns with aliases, concatenates name parts, and returns only distinct department values.

Build a cross join and a natural join, then state in writing when each is useful and when each is dangerous.

Use a non-equijoin to map a numeric value into a banded range table, and verify the boundaries return exactly one band.

Write single-row and multi-row subqueries in the WHERE clause, choosing between =, IN, ANY, and ALL and justifying the operator choice.

Convert three of week 1's join queries into equivalent subquery formulations and confirm the row counts match.

Apply COUNT, SUM, AVG, MIN, and MAX with and without GROUP BY, and explain in writing why AVG ignores NULLs while COUNT(*) does not.

Group by two columns and use HAVING to filter groups, distinguishing clearly between WHERE row filtering and HAVING group filtering.

Use character functions (SUBSTR, INSTR, LPAD, TRIM, UPPER) and numeric functions (ROUND, TRUNC, MOD) to reshape output columns.

Apply NVL and COALESCE inside aggregates so NULL-bearing columns produce the expected totals.

Identify and fix three queries that illegally mix an aggregate with a non-grouped column in the SELECT list.

Sort result sets with ORDER BY using column aliases, positional references, multiple keys, and explicit ASC/DESC and NULLS FIRST/LAST.

Filter rows with BETWEEN, IN, LIKE (including escaped wildcards), and IS NULL, and predict which rows each predicate excludes.

Use date functions (MONTHS_BETWEEN, ADD_MONTHS, LAST_DAY, NEXT_DAY, TRUNC on dates) to answer reporting-style date questions.

Apply TO_CHAR, TO_DATE, and TO_NUMBER with explicit format models, and explain when implicit conversion silently changes a result or breaks an index.

Use the CASE expression and DECODE to produce conditional output columns, and rewrite one as the other to show equivalence.

Combine result sets with UNION, UNION ALL, INTERSECT, and MINUS, and state the exact row-count difference between UNION and UNION ALL.

Diagnose and fix a set-operator query that fails because column counts or data types do not match across the two SELECTs.

Insert rows with INSERT ... VALUES and INSERT ... SELECT, then verify each with a targeted SELECT.

Update and delete rows using a subquery-driven WHERE clause, and confirm affected row counts before committing.

Demonstrate transaction control with COMMIT, ROLLBACK, and SAVEPOINT, showing what survives each boundary.

Create a sequence, use NEXTVAL and CURRVAL to populate a primary key, and create a synonym plus an index on a frequently filtered column.

Create a simple view, a view with a CHECK OPTION, and a read-only view, then test which DML each accepts.

Create a private temporary table and a global temporary table, and state the scope and lifetime difference between them.

Query USER_TABLES, USER_VIEWS, USER_INDEXES, USER_SEQUENCES, and USER_CONSTRAINTS to answer five object-inventory questions.

Join USER_TAB_COLUMNS to USER_TABLES to list column definitions for your own objects only.

Complete two full-length timed practice exams under exam conditions and log every missed question by domain.

Re-teach the two weakest domains by rewriting each missed question as a fresh query and explaining the fix aloud.

Rehearse the highest-frequency traps: NULL handling in aggregates and joins, HAVING versus WHERE, UNION versus UNION ALL, and implicit conversion.

Confirm readiness by scoring at or above 80 percent on a third timed set covering all twelve domains.