I'm having trouble with NULL statement in SQLITE. I added NULL in cases there is no info to be filled, but once I run the code the IDE throws an error.
CREATE TABLE tenants (
Apartment_Number INT(4),
Family_Name VARCHAR(8) NULL,
Sur_Name VARCHAR(14) NULL,
Home_Number INT(4),
Mobile_Number int(10),
PRIMARY KEY (Apartment_Number )
);
INSERT INTO tenants
VALUES
(101,,,201,0544431263),
(102,,,202,0544431263),
(103,'Shklobin','marta',203,0544431263),
(104,'arman','charles',204,0544431263);
SELECT * FROM tenants;
The empty spaces are where I hope the IDE will fill with NULL values.
The error I receive:
Error: near line 12: near ",": syntax error.
If I remove the NULL statement, the IDE runs the code with no errors.
Official documentation indicates that
The default value of each column is NULL.
The default behavior is also to allow NULL in each column. The behavior only changes if NOT NULL and/or DEFAULT ... constraints are specified. You should get the same error whether or not you have the lone NULL keyword as shown in the question code. My testing shows that the following does not suppress the error as implied in the question--in other words, the following change results in the same error.
Family_Name VARCHAR(8),
Sur_Name VARCHAR(14),
The following alternative INSERT statements will work:
INSERT INTO tenants
(Apartment_Number, Home_Number, Mobile_Number)
VALUES
(101,201,0544431263),
(102,202,0544431263);
INSERT INTO tenants
VALUES
(103,'Shklobin','marta',203,0544431263),
(104,'arman','charles',204,0544431263);
or
INSERT INTO tenants
VALUES
(101, NULL, NULL,201,0544431263),
(102, NULL, NULL,202,0544431263),
(103,'Shklobin','marta',203,0544431263),
(104,'arman','charles',204,0544431263);
Related
CREATE TABLE IF NOT EXISTS developer (id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT, skill TEXT, yearsOfExperience INTEGER );
INSERT INTO developer(name, skill, yearsOfExperience) VALUES ('Simon', 'Ionic', '4');
INSERT INTO developer(name, skill, yearsOfExperience) VALUES ('Jorge', 'Firebase', '2');
INSERT INTO developer(name, skill, yearsOfExperience) VALUES ('Max', 'Startup', '5');
error:
Incorrect syntax near 'IF', Expecting'.', ID, or QOUTED_ID.
An expression of non-boolean type specified in a context where a condition is expected.
Incorrect syntax near 'developer'.
Incorrect syntax near 'developer'. Expecting '('.
Incorrect syntax near 'id'. Expecting '(' or SELECT.
I have created a table as below:
CREATE TABLE case_status(data_entry_timestamp DATETIME DEFAULT (datetime('now','localtime')) NOT NULL,
case_number TEXT PRIMARY KEY NOT NULL,
case_name TEXT DEFAULT MISSING,
death_reportdate DATE CONSTRAINT death_reportdate_chk CHECK (death_reportdate==strftime('%Y-%m-%d',death_reportdate)),
);
The column death_reportdate need to have a date with pre-defined format (e.g. 2000-12-31). I created the table, inserted some rows of data, and then try to modified data in death_reportdate, the check rule seems to be bypassed when I enter some random string to it.
What have I done wrong?
You had an extra comma at the end. Correct code:
CREATE TABLE case_status(data_entry_timestamp DATETIME DEFAULT (datetime('now','localtime')) NOT NULL,
case_number TEXT PRIMARY KEY NOT NULL,
case_name TEXT DEFAULT MISSING,
death_reportdate DATE CONSTRAINT death_reportdate_chk CHECK (death_reportdate==strftime('%Y-%m-%d',death_reportdate))
)
it is an old Topic but i had the the same Problem. if the strftime method Fails to Format the string( a bad Input) it retuns null, so you have to check is not null in the end
Here is another solution which works like a charm:
`date` DATE CHECK(date IS strftime('%Y-%m-%d', date))
This also works with the time:
`time` TIME CHECK(time IS strftime('%H:%M:%S', time))
Use this to define your column. I think that is a more elegant solution than checking for null value.
First, two small notes.
I'm using the TEXT type since SQLite does not have "real types." It has 5 column "affinities", INTEGER, TEXT, BLOB, REAL, and NUMERIC. If you say DATE then it uses NUMERIC which can behave a little weirdly in my opinion. I find it best to explicitly use one of the 5 affinities.
I'm using date(...) instead of strftime('%Y-%m-%d', ...) because they are the same thing.
Let's break down why the original question did not work.
DROP TABLE IF EXISTS TEMP.example;
CREATE TEMPORARY TABLE example (
deathdate TEXT CHECK (deathdate == date(deathdate))
);
INSERT INTO TEMP.example (deathdate) VALUES ('2020-01-01');
INSERT INTO TEMP.example (deathdate) VALUES ('a');
INSERT INTO TEMP.example (deathdate) VALUES (NULL);
SELECT * FROM TEMP.example;
Running this lets all three values get into the database. Why? Let's check the documentation for CHECK constraints.
If the result is zero (integer value 0 or real value 0.0), then a constraint violation has occurred. If the CHECK expression evaluates to NULL, or any other non-zero value, it is not a constraint violation.
If you run SELECT 'a' == date('a'); you'll see it is NULL. Why? Check SELECT date('a'); and you'll see it is also NULL. Huh, maybe the documentation for == can help?
Note that there are two variations of the equals and not equals operators. Equals can be either = or ==. [...]
The IS and IS NOT operators work like = and != except when one or both of the operands are NULL. In this case, if both operands are NULL, then the IS operator evaluates to 1 (true) and the IS NOT operator evaluates to 0 (false). If one operand is NULL and the other is not, then the IS operator evaluates to 0 (false) and the IS NOT operator is 1 (true). It is not possible for an IS or IS NOT expression to evaluate to NULL.
We need to use IS, not ==, and trying that we see that 'a' no longer gets in.
DROP TABLE IF EXISTS TEMP.example;
CREATE TEMPORARY TABLE example (
deathdate TEXT CHECK (deathdate IS date(deathdate))
);
INSERT INTO TEMP.example (deathdate) VALUES ('2020-01-01');
INSERT INTO TEMP.example (deathdate) VALUES ('a');
INSERT INTO TEMP.example (deathdate) VALUES (NULL);
SELECT * FROM TEMP.example;
If you don't want NULL to get in, simple change it to deathdate TEXT NOT NULL CHECK (deathdate IS date(deathdate))
I am trying to create 3 tables but I am getting this error:
CREATE TABLE dj_abonent
(
dj_klientID INT NOT NULL PRIMARY KEY,
emer_klienti varchar2(10),
mbiemer_klienti VARCHAR2(10),
sasia_cel INT
);
CREATE TABLE dj_phones
(
phone_number varchar2(12),
activated number(1) default 0,
activation_date date default null,
CONSTRAINT dj_phone_number_check
CHECK (substr(phone_number,1,5) in( '35566','35567','35568','35569') ),
CONSTRAINT dj_activated_check
CHECK (activated in(1,0) )
dj_KlientID int FOREIGN KEY REFERENCES dj_Abonenti(dj_KlientID)
);
CREATE TABLE dj_telef
(
start_time date,
end_time date,
abonent_1 varchar2(10),
abonent_2 varchar2(10)
);
Error at Command Line : 26 Column : 17
Error report -
SQL Error: ORA-00907: missing right parenthesis
00907. 00000 - "missing right parenthesis"
*Cause:
*Action:
The line number is from your SQL Developer script window, which isn't entirely helpful as it doesn't seem to align with the issue. There may be other things too but you're missing a comma after your check constraint (just like a previous question). But you should put the constraints at the end of the command:
CREATE TABLE dj_phones
(
phone_number varchar2(12),
activated number(1) default 0,
activation_date date default null,
dj_KlientID int FOREIGN KEY REFERENCES dj_Abonenti(dj_KlientID)
CONSTRAINT dj_phone_number_check
CHECK (substr(phone_number,1,5) in( '35566','35567','35568','35569') ),
CONSTRAINT dj_activated_check
CHECK (activated in(1,0) )
);
You might find it easier to debug these issues if you ran one statement at a time, either with the run statement command (control-enter), or by highlighting the text one one command and using run script (F5).
I have a TCL script where i generate a SQLite table:
DB eval {CREATE TABLE StressDat2( LC int NOT NULL, EID int NOT NULL, Xtens float, Ytens float ) }
When I try to write NULL values they get accepted anyhow. How can I from Tcl, when generating my table, set the ABORT option which shall handle writing attempts of NULL values?
The Xtens and Ytens columns do not have a NOT NULL constraint.
(The default conflict resolution algorithm is ABORT; you don't need to set it.)
It depends on how do you insert data into the table. If you also do it with Tcl, you need to be aware, that Tcl doesn't understand the idea of NULL value.
Therefore, this is WRONG:
set lc ""
set eid ""
set xtens ""
set utens ""
DB eval {INSERT INTO StressDat2 (LC, EID, Xtens, Ytens) VALUES ($lc, $eid, $xtens, $ytens);
You're obviously inserting empty strings, not null values. To insert null, use null keyword in SQL statement.
This is CORRECT:
DB eval {INSERT INTO StressDat2 (LC, EID, Xtens, Ytens) VALUES (NULL, NULL, NULL, NULL);
Finally, a word about "ABORT" conflict resolution in NOT NULL constraint, that you mentioned. You said this is blank in SQLiteStudio and not "ABORT", as you would like to. Well, the "ABORT" algorithm is a default algorithm used by sqlite when no algorithm was defined, so even you have it blank (default), it means it's "ABORT". Read this for more details: http://sqlite.org/lang_createtable.html
I have a table named CUSTOMER, with few columns. One of them is Customer_ID.
Initially Customer_ID column WILL NOT accept NULL values.
I've made some changes from code level, so that Customer_ID column will accept NULL values by default.
Now my requirement is that, I need to again make this column to accept NULL values.
For this I've added executing the below query:
ALTER TABLE Customer MODIFY Customer_ID nvarchar2(20) NULL
I'm getting the following error:
ORA-01451 error, the column already allows null entries so
therefore cannot be modified
This is because already I've made the Customer_ID column to accept NULL values.
Is there a way to check if the column will accept NULL values before executing the above query...??
You can use the column NULLABLE in USER_TAB_COLUMNS. This tells you whether the column allows nulls using a binary Y/N flag.
If you wanted to put this in a script you could do something like:
declare
l_null user_tab_columns.nullable%type;
begin
select nullable into l_null
from user_tab_columns
where table_name = 'CUSTOMER'
and column_name = 'CUSTOMER_ID';
if l_null = 'N' then
execute immediate 'ALTER TABLE Customer
MODIFY (Customer_ID nvarchar2(20) NULL)';
end if;
end;
It's best not to use dynamic SQL in order to alter tables. Do it manually and be sure to double check everything first.
Or you can just ignore the error:
declare
already_null exception;
pragma exception_init (already_null , -01451);
begin
execute immediate 'alter table <TABLE> modify(<COLUMN> null)';
exception when already_null then null;
end;
/
You might encounter this error when you have previously provided a DEFAULT ON NULL value for the NOT NULL column.
If this is the case, to make the column nullable, you must also reset its default value to NULL when you modify its nullability constraint.
eg:
DEFINE table_name = your_table_name_here
DEFINE column_name = your_column_name_here;
ALTER TABLE &table_name
MODIFY (
&column_name
DEFAULT NULL
NULL
);
I did something like this, it worked fine.
Try to execute query, if any error occurs, catch SQLException.
try {
stmt.execute("ALTER TABLE Customer MODIFY Customer_ID nvarchar2(20) NULL");
} catch (SQLException sqe) {
Logger("Column to be modified to NULL is already NULL : " + sqe);
}
Is this correct way of doing?
To modify the constraints of an existing table
for example... add not null constraint to a column.
Then follow the given steps:
1) Select the table in which you want to modify changes.
2) Click on Actions.. ---> select column ----> add.
3) Now give the column name, datatype, size, etc. and click ok.
4) You will see that the column is added to the table.
5) Now click on Edit button lying on the left side of Actions button.
6) Then you will get various table modifying options.
7) Select the column from the list.
8) Select the particular column in which you want to give not null.
9) Select Cannot be null from column properties.
10) That's it.