CURRENT_DATE, CURRENT_TIMESTAMP, NOW() in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the current date in PostgreSQL.

PostgreSQL

SELECT [1];

Drag options to blanks, or click blank then click option'

ANOW()

BCURRENT_DATE

CCURRENT_TIMESTAMP

DGETDATE()

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOW() or CURRENT_TIMESTAMP returns date and time, not just date.

Using GETDATE() is not valid in PostgreSQL.

The CURRENT_DATE function returns the current date without time in PostgreSQL.

2fill in blank

medium

Complete the code to select the current date and time in PostgreSQL.

PostgreSQL

SELECT [1];

Drag options to blanks, or click blank then click option'

ACURRENT_DATE

BSYSDATE

CNOW()

DGETDATE()

Attempts:

3 left

💡 Hint

Common Mistakes

Using CURRENT_DATE returns only the date, not time.

GETDATE() and SYSDATE are not PostgreSQL functions.

The NOW() function returns the current date and time in PostgreSQL.

3fill in blank

hard

Fix the error in the code to select the current timestamp in PostgreSQL.

PostgreSQL

SELECT [1];

Drag options to blanks, or click blank then click option'

ASYSDATE

BCURRENT_DATE

CGETDATE()

DCURRENT_TIMESTAMP

Attempts:

3 left

💡 Hint

Common Mistakes

Using GETDATE() or SYSDATE causes errors in PostgreSQL.

Using CURRENT_DATE returns only the date, not timestamp.

CURRENT_TIMESTAMP returns the current date and time in PostgreSQL and is the correct keyword to use here.

4fill in blank

hard

Fill both blanks to select the current date and current timestamp in PostgreSQL.

PostgreSQL

SELECT [1] AS today, [2] AS now_time;

Drag options to blanks, or click blank then click option'

ACURRENT_DATE

BNOW()

CCURRENT_TIMESTAMP

DGETDATE()

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOW() in the first blank returns date and time, not just date.

Using GETDATE() is invalid in PostgreSQL.

CURRENT_DATE returns the current date, and CURRENT_TIMESTAMP returns the current date and time.

5fill in blank

hard

Fill all three blanks to select current date, current timestamp, and current time in PostgreSQL.

PostgreSQL

SELECT [1] AS today, [2] AS now_time, [3] AS just_time;

Drag options to blanks, or click blank then click option'

ACURRENT_DATE

BCURRENT_TIMESTAMP

CCURRENT_TIME

DNOW()

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOW() for time only is incorrect because it returns date and time.

Mixing up CURRENT_TIME and CURRENT_TIMESTAMP.

CURRENT_DATE returns the date only, CURRENT_TIMESTAMP returns date and time, and CURRENT_TIME returns the current time only.

Practice

1. Which PostgreSQL function returns only the current date without the time component?

easy

A. CURRENT_DATE

B. CURRENT_TIMESTAMP

C. NOW()

D. DATE_PART()

Solution

1. Step 1: Understand the function outputs

   CURRENT_DATE returns only the date part (year-month-day) without time.

2. Step 2: Compare with other functions

   CURRENT_TIMESTAMP and NOW() return both date and time, while DATE_PART() extracts parts but is not a current date function.

3. Final Answer:

   CURRENT_DATE -> Option A

4. Quick Check:

   Only date, no time = CURRENT_DATE [OK]

Hint: Only date? Use CURRENT_DATE [OK]

Common Mistakes:

• Confusing CURRENT_TIMESTAMP with CURRENT_DATE
• Using NOW() when only date is needed
• Thinking DATE_PART() returns current date

2. Which of the following is the correct syntax to get the current timestamp in PostgreSQL?

easy

A. SELECT CURRENT_DATE();

B. SELECT CURRENT_TIMESTAMP;

C. SELECT CURRENT_TIME();

D. SELECT NOW;

Solution

1. Step 1: Check function syntax

   CURRENT_TIMESTAMP is a special function and does not require parentheses.

2. Step 2: Validate other options

   SELECT CURRENT_DATE(); uses parentheses incorrectly with CURRENT_DATE. SELECT CURRENT_TIME(); returns only the time part (time type), not full timestamp. SELECT NOW; misses required parentheses for NOW(). SELECT CURRENT_TIMESTAMP; is the correct and preferred standard syntax.

3. Final Answer:

   SELECT CURRENT_TIMESTAMP; -> Option B

4. Quick Check:

   Standard timestamp function = CURRENT_TIMESTAMP [OK]

Hint: CURRENT_TIMESTAMP has no parentheses [OK]

Common Mistakes:

• Adding parentheses to CURRENT_DATE
• Omitting parentheses for NOW()
• Confusing function syntax

3. What will be the output type of the following query?
SELECT CURRENT_DATE, CURRENT_TIMESTAMP, NOW();

medium

A. Error due to mixing functions

B. Three columns: date, date, date

C. Three columns: timestamp without time zone, timestamp without time zone, timestamp without time zone

D. Three columns: date, timestamp with time zone, timestamp with time zone

Solution

1. Step 1: Identify each function's return type

   CURRENT_DATE returns a date type (no time). CURRENT_TIMESTAMP and NOW() return timestamp with time zone.

2. Step 2: Confirm output columns

   The query returns three columns: one date and two timestamps with time zone.

3. Final Answer:

   Three columns: date, timestamp with time zone, timestamp with time zone -> Option D

4. Quick Check:

   Types: date, timestamptz, timestamptz = Three columns: date, timestamp with time zone, timestamp with time zone [OK]

Hint: CURRENT_DATE = date; others = timestamp with time zone [OK]

Common Mistakes:

• Assuming all return date only
• Thinking NOW() returns date
• Expecting syntax error

4. You wrote this query but it gives an error:
SELECT CURRENT_DATE();
What is the problem?

medium

A. You must cast CURRENT_DATE to text

B. CURRENT_DATE requires a parameter inside parentheses

C. CURRENT_DATE is not a function and should not have parentheses

D. CURRENT_DATE is deprecated and replaced by NOW()

Solution

1. Step 1: Check function usage

   CURRENT_DATE is a special keyword, not a function, so it does not accept parentheses.

2. Step 2: Understand error cause

   Using parentheses causes syntax error because PostgreSQL expects no parentheses for CURRENT_DATE.

3. Final Answer:

   CURRENT_DATE is not a function and should not have parentheses -> Option C

4. Quick Check:

   No parentheses with CURRENT_DATE [OK]

Hint: No parentheses with CURRENT_DATE [OK]

Common Mistakes:

• Adding () to CURRENT_DATE
• Thinking CURRENT_DATE needs parameters
• Confusing with NOW() syntax

5. You want to insert the current date and time into a table with columns created_date DATE and created_time TIMESTAMP. Which INSERT statement is correct?

hard

A. INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_DATE, NOW());

B. INSERT INTO table_name (created_date, created_time) VALUES (NOW(), CURRENT_DATE);

C. INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_TIMESTAMP, CURRENT_DATE);

D. INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_DATE(), CURRENT_TIMESTAMP());

Solution

1. Step 1: Match data types with values

   created_date is DATE type, so CURRENT_DATE fits. created_time is TIMESTAMP, so NOW() fits.

2. Step 2: Check syntax correctness

   INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_DATE, NOW()); uses correct functions and order. INSERT INTO table_name (created_date, created_time) VALUES (NOW(), CURRENT_DATE); swaps types incorrectly. INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_TIMESTAMP, CURRENT_DATE); uses timestamp for date column (wrong type). INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_DATE(), CURRENT_TIMESTAMP()); uses parentheses incorrectly with CURRENT_DATE and CURRENT_TIMESTAMP.

3. Final Answer:

   INSERT INTO table_name (created_date, created_time) VALUES (CURRENT_DATE, NOW()); -> Option A

4. Quick Check:

   Date = CURRENT_DATE, Timestamp = NOW() [OK]

Hint: Match DATE with CURRENT_DATE, TIMESTAMP with NOW() [OK]

Common Mistakes:

• Swapping date and timestamp values
• Using parentheses with CURRENT_DATE
• Using CURRENT_TIMESTAMP for DATE column