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The table "foo" is defined as follows: CREATE TABLE foo (bar
TEXT); Next, four SQL statements were executed in the following order. INSERT INTO foo VALUES ('bar'); -------- (1)
ALTER TABLE foo ADD COLUMN c1 TEXT; ---- (2) ALTER
TABLE foo ADD UNIQUE (c1); ------- (3) ALTER TABLE foo
DROP COLUMN bar; ------- (4) Select the correct statement from those below.
Suggested Answer: E
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32 comments · newest first
EL
Elden
10 months ago
Not sure about that, seems like a mistake to me.
LA
Latosha
11 months ago
No errors until the last statement, I agree!
WI
Winfred
11 months ago
Surprised they dropped 'bar' after adding c1!
CH
Chery
11 months ago
I think the unique constraint on c1 will cause issues later.
HA
Hayley
11 months ago
The first insert should work fine.
LA
Lasandra
12 months ago
I practiced a similar question, and I think no errors should occur with these statements, but I’m a bit confused about the unique constraint part.
GR
Gregg
12 months ago
For the fourth statement, I feel like dropping a column that was just added could lead to an error, but I need to double-check that.
AN
Annelle
12 months ago
I'm not entirely sure, but I remember something about adding a unique constraint that could cause issues if there are duplicates.
JA
Jacquelyne
1 year ago
I think the first statement should work fine since we're just inserting a value into the table.
DE
Derick
1 year ago
I'm a bit unsure about this one. The question seems straightforward, but I want to make sure I'm not missing any subtle details. I'll need to review the SQL statements and the table definition a few times to make sure I understand what's going on.
CO
Coral
1 year ago
This is a good test of my SQL knowledge. I'll need to carefully analyze the sequence of statements and the table structure to identify the point where an error might occur. I'm feeling confident I can solve this.
MI
Mirta
1 year ago
Okay, I think I've got this. The key is to understand the impact of each SQL statement on the table structure. I'll need to consider the column changes and the unique constraint to determine where the error might happen.
NO
Noble
1 year ago
Hmm, I'm a bit confused by the question. The table definition and the SQL statements seem straightforward, but I'm not sure which one might cause an error. I'll need to think this through step-by-step.
MA
Mauricio
1 year ago
This looks like a tricky SQL question. I'll need to carefully read through the table definition and the sequence of SQL statements to figure out where the potential error might occur.
SH
Shawna
2 years ago
I'd go with D. Dropping a column that's part of the primary key has got to cause an error, right?
JO
Joaquin
2 years ago
D) An error occurs when executing the (4) SQL statement.
DA
Dana
2 years ago
C) An error occurs when executing the (3) SQL statement.
MO
Mohammad
2 years ago
B) An error occurs when executing the (2) SQL statement.
AL
Aleisha
2 years ago
A) An error occurs when executing the (1) SQL statement.
JU
Jules
2 years ago
But the UNIQUE constraint should be added to a column, not the table itself. So, I think an error occurs when executing the (3) SQL statement.
GI
Gianna
2 years ago
Haha, dropping the 'bar' column? That's a bold move, let's see if it works!
EV
Evette
2 years ago
User3: I believe an error occurs when executing the (3) SQL statement.
MA
Martina
2 years ago
User2: No error is generated.
DE
Delfina
2 years ago
User1: I think an error occurs when executing the (4) SQL statement.
ON
Ona
2 years ago
I believe no error is generated.
GL
Glen
2 years ago
Hmm, I'm not sure. Maybe the (2) statement would cause an error since you can't add a column to a table that already has data in it.
VI
Vivienne
2 years ago
I think the answer is E. No error is generated. The table has been modified successfully, and the data remains intact.
LA
Lanie
2 years ago
So, the correct statement is E. No error is generated.
JI
Jill
2 years ago
The data remains intact after the alterations.
AM
Amina
2 years ago
I agree, the table has been modified successfully.
LE
Lenna
2 years ago
I think the answer is E. No error is generated.
JU
Jules
2 years ago
I think an error occurs when executing the (3) SQL statement.