I have started my journey in learning SQL and right I am having trouble creating and inserting data into tables. Here is the code that I have tried, I get an error message saying that there aren't enough values. I am using Oracle.
Create table project
(
proj_id number(10),
medic_name varchar2(10),
purpose varchar2(12),
start_date date,
end_date date,
pi_id null,
CONSTRAINT pkprojid primary key (proj_id),
CONSTRAINT fkproject foreign key (pi_id) references researcher
);
alter session set nls_date_format = 'mm/dd/yyyy';
Insert into project values (PR001, 'Medic1', 'heart', '09/01/2017', '07/31/2019');
Insert into project values (PR002, 'Medic1', 'diabetes', '10/01/2016', '07/31/2020);
Insert into project values (PR003, 'Medic3', 'lung', '11/1/2014', '12/31/2020');
Insert into project values (PR004, 'Medic3', 'blood', '01/10/2017', '07/31/2019');
Insert into project values (PR005, 'Medic5', 'blood', '07/10/2018', '01/31/2020');
alter session set nls_date_format = 'mm/dd/yyyy';
Insert into project values (PR001, 'Medic1', 'heart', '09/01/2017', '07/31/2019');
Issues:
Your table has 6 columns, you are only passing 5 for insert; it seems like you are missing last column (pi_id), hence the error message that you are getting. If you want to skip the last column (which is possible since it is declared as nullable), you can explictly list the column when inserting
first column (proj_id) is of number datatype; PR001 is not a number (neither a string, since it is not quoted: this is a syntax error); did you mean 1 instead? Or, if you want to insert string values, you need to change the datatype of column proj_id to varchar(N) (N being the maximum length of the string, in bytes).
Here is an insert statement that should work for your current table definition:
insert into project(proj_id, medic_name, purpose, start_date, end_date)
values (1, 'Medic1', 'heart', '09/01/2017', '07/31/2019');
Note: there is a missing quote at the end of the date on the second insert statement; I assume that this is a typo.
Related
I have a simple table like this:
CREATE TABLE IF NOT EXISTS myval
(
id integer NOT NULL DEFAULT nextval('myval_myval_id_seq'::regclass),
name character varying(255),
CONSTRAINT "PK_aa671c3359a0359082a84ecb801" PRIMARY KEY (id)
)
the sequence definition is:
CREATE SEQUENCE IF NOT EXISTS myval_myval_id_seq
INCREMENT 1
START 1
MINVALUE 1
MAXVALUE 2147483647
CACHE 1
OWNED BY myval.myval_id;
when I insert data along with the primary key:
INSERT INTO myval(id, name) VALUES (1, 'sdf');
INSERT INTO myval(id, name) VALUES (2, 'sdf');
INSERT INTO myval(id, name) VALUES (3, 'sdf');
INSERT INTO myval(id, name) VALUES (4, 'sdf');
then, I insert it without the PK:
INSERT INTO myval(name) VALUES ('new sdf');
it gives an error saying:
duplicate key value violates unique constraint "PK_aa671c3359a0359082a84ecb801",
DETAIL: Key (myval_id)=(1) already exists.
I expected it to start with PK value of 5 but, instead it gives an error. Can we configure postgres to skip conflicting values and generate from the closest available value to use instead of throwing an error?
The best way to avoid such conflicts is to use identity columns - in this case a GENERATED ALWAYS AS IDENTITY seems the right option.
CREATE TABLE IF NOT EXISTS myval
(
id integer GENERATED ALWAYS AS IDENTITY,
name character varying(255),
CONSTRAINT "PK_aa671c3359a0359082a84ecb801" PRIMARY KEY (id)
);
This will work like a sequence (serial), however it will fail if the user tries to manually insert a value in this column
INSERT INTO myval (id,name)
VALUES (1,'foor');
ERROR: cannot insert a non-DEFAULT value into column "id"
DETAIL: Column "id" is an identity column defined as GENERATED ALWAYS.
TIP: Use OVERRIDING SYSTEM VALUE to override.
If for whatever reason you must override this behavior in a certain INSERT statement you can do so using OVERRIDING SYSTEM VALUE, as the error message above suggests
INSERT INTO myval (id,name) OVERRIDING SYSTEM VALUE
VALUES (1,'foo');
You might be able to achieve a sequential value using serial even if the user screws things up with inserts, e.g. using trigger functions. But such an architecture is hard to maintain and imho is definitely not worth the trouble.
Demo: db<>fiddle
I have a table where records have a (begin, end) time window of existence (for things like employement duration, birth and death, rent duration, ...)
begin IS NULL or end IS NULL if there is no bound.
CREATE TABLE mytable(
id int primary key,
value int, --UNIQUE at any point in time
begin datetime NULL,
end datetime NULL
);
I want column value to be unique at any point in time.
INSERT INTO mytable VALUES(1, 1, '2021-07-23', '2021-07-24'),(2, 1, '2021-07-25', NULL);
Is OK
Whereas
INSERT INTO mytable VALUES(1, 1, '2021-07-23', '2021-07-30'),(2, 1, '2021-07-25', NULL);
Is not OK, because both records have value=1 and overlapping time windows.
Is there a way to enforce such a constraint in SQL ?
You can't do this on the table, no, as there's nothing to make UNIQUE on.
What you could do, however, is use a VIEW to enforce it.
Firstly, let's create your table. I assume the columns datetime, should actually be begin and end; I recommend against these names as they are reserved keywords. As such I am calling them DateBegin and DateEnd. I am also assuming that they are date only (no time portion) values and so define them as a date not a datetime:
CREATE TABLE dbo.mytable(ID int primary key,
Value int,
[BeginDate] date NULL,
[EndEnd] date NULL);
And we'll INSERT your first 2 rows, as they are "ok":
INSERT INTO dbo.mytable (ID, Value, BeginDate, EndDate)
VALUES(1, 1, '20210723', '20210724'),
(2, 1, '20210725', NULL);
Now we need to make a VIEW, but we need one row per date. As such you'll want to create a Calendar Table. I'm not going to cover how to create one here, but there are literally 100's of articles, such as there on SQL Server Central: Bones of SQL - The Calendar Table, Calendar Tables in T-SQL.
Once you have your Calendar table, you can create the VIEW below, which JOINs the data in your table to the calendar table. We're going to make it so that the VIEW just returns the columns value and the date. WE're also going to schemabind it; this means we'll be able to add an UNIQUE INDEX to it:
CREATE VIEW dbo.MyView
WITH SCHEMABINDING
AS
SELECT MT.[Value],
CT.CalendarDate
FROM dbo.MyTable MT
JOIN dbo.CalendarTable CT ON MT.BeginDate <= CT.CalendarDate --I assume, despite your schema, MT.BeginDate can't be NULL
AND (MT.EndDate >= CT.CalendarDate OR MT.EndDate IS NULL);
Now we have a VIEW that has a row for each date, and for each value. This means we can now create our UNIQUE INDEX:
CREATE UNIQUE CLUSTERED INDEX MyIndex ON dbo.MyView ([Value], CalendarDate);
Now if we try to INSERT a row that is on the same date and value, we'll get an error:
INSERT INTO dbo.MyTable (ID, Value, BeginDate, EndDate)
VALUES(3, 1, '20210720', '20210723');
Cannot insert duplicate key row in object 'dbo.MyView' with unique index 'MyIndex'. The duplicate key value is (1, 2021-07-23).
I have simple table where I want to insert new records.
The table has an ID column which is set as identity and generated always.
StoreGeneratedPattern=Identity is set for the ID column.
When I try to add a new record to the table in VB.Net
rec = New TEST_TABLE
ctx.TEST_TABLE.Add(rec)
ctx.SaveChanges()
It results in get ORA-00947: not enough values.
It seems as if the Entity Framework is creating an invalid SQL request. Something like INSERT INTO TEST_TABLE (ID, NAME) VALUES('Tom');.
How can I solve this situation?
How can I check, which SQL request is sent to Oracle?
Adding lines with direct sql queries works perfectly:
INSERT INTO TEST_TABLE (NAME) VALUES('Tom');
1 line affected.
The table's schemata is as follows:
CREATE TABLE "TEST_TABLE"
("NAME" VARCHAR2(20) NOT NULL ENABLE,
"ID" NUMBER GENERATED ALWAYS AS IDENTITY
MINVALUE 1 MAXVALUE 999999999999999999999999999 INCREMENT BY 1 START WITH 1 NOORDER NOCYCLE NOT NULL ENABLE,
CONSTRAINT "TEST_TABLE_PK" PRIMARY KEY ("ID") ENABLE
);
CREATE UNIQUE INDEX "TEST_TABLE_PK" ON "TEST_TABLE" ("ID");
Edit: I solved the problem: StoreGeneratedValue=Identity was set for NAME, not for ID. After correcting this, everything just works fine.
"Not enough values" comes when there are too few values passed on insert statement. Like this
insert into table_name(col1, col2, col3) values(1, 2)
I've passed 2 values whereas there are 3 columns listed in the beginning of insert. Thus, I almost sure, underlying insert statement lacks of a value.
You need to check content of inserting routine on VB side if posiible.
As a workaround I'd try to replace "GENERATED ALWAYS" with "GENERATED BY DEFAULT" and run the VB code with StoreGeneratedPattern=None
I'm having a hard time creating a simple table:
CREATE TABLE `csat` (
`csat_id` INT NOT NULL AUTO_INCREMENT,
`value` INT,
`month` DATE NOT NULL,
PRIMARY KEY (`csat_id`)
);
CREATE TABLE `migrated` (
`migrated_id` INT NOT NULL AUTO_INCREMENT,
`title` INT,
`description` INT,
`month` DATE NOT NULL,
PRIMARY KEY (`migrated_id`)
);
INSERT INTO csat
VALUES (1, 1, 2017-06-15);
INSERT INTO migrated
VALUES (1, 2, 2018-06-15);
I get the error:
Data truncation: Incorrect date value: '1996' for column 'month' at row 1
It seems like my date is in the right format:
https://www.w3schools.com/sql/func_mysql_date.asp
I'm also wondering why I need to specify a value on the csat_id, because I thought SQL would just put that in for me since its the primary key.
You have to wrap your date values in single quotation marks: '2017-06-15', not 2017-06-15. Right now, MySQL is evaluating this as 2017 minus 6 minus 15, which comes to 1996.
Also, when inserting, it's best to specify the columns you're inserting into. And if your column is set to AUTO_INCREMENT, you don't need to specify it:
INSERT INTO csat
(`value`, `month`)
VALUES
(1, '2017-06-15');
I would also consider changing your column names. Perhaps make "value" more descriptive (value of what?) And month is misleading, since it's actually a date-type column.
You haven't said which database server you're using, but generally speaking dates are inputted as strings.
You should try the following inserts;
INSERT INTO csat (`csat_id`, `value`, `month`)
VALUES (1, 1, '2017-06-15');
INSERT INTO migrated (`migrated_id`, `title`, `description`, `month`)
VALUES (1, 2, 2, '2018-06-15');
Also, you should specify which columns you're inserting into. This prevents data from being entered into the wrong fields, especially when schema changes occur.
SQL does auto increment primary key fields (if defined that way). However, you had to define it in your insert statements because you didn't specify the columns you were inserting to.
Try this instead;
INSERT INTO csat (`value`, `month`)
VALUES (1, '2017-06-15');
INSERT INTO migrated (`title`, `description`, `month`)
VALUES (2, 2, '2018-06-15');
I guess you missed the single qoutes (as per Sql standards) at first in your date and then while inserting even if the column is autoincrement you need to specify columns other than the autoincrement column so as to make sure the data you are inserting belongs to that specific column or not
Try this
INSERT INTO
csat(value,month) values
(1,'2017-06-15')
Facing some issues with the auto-increment property in postgresql
I created a table say emp
create table emp
( empid serial,
empname varcha(50),
primary key (empid)
);
I inserted one value with empid as blank:
insert into emp (empname) values ('test1');
Next insert by specifying the empid value:
insert into emp (empid,empname) values (2,'test2');
Now, the next time if I insert a value without specifying the empid value, it will give an error because it will try to insert the empid as 2:
insert into emp (empname) values ('test3');
ERROR: duplicate key value violates unique constraint "emp_pkey"
DETAIL: Key (empid)=(2) already exists.
Can someone help me with a workaround for this issue so that with or without specifying a value, the autoincrement should pick up the max(value) +1 ??
Thanks
You can't cleanly mix use of sequences and fixed IDs. Inserting values without using the sequence won't update the sequence, so you'll get collisions.
If you're doing your manual insertions in a bulk load phase or something you can:
BEGIN
LOCK TABLE the_table IN ACCESS EXCLUSIVE MODE
Do your INSERTs
SELECT setval('seq_name', 14), replacing 14 with the new sequence value. This can be a subquery against the table.
COMMIT
... but in general, it's better to just avoid mixing sequence ID generation and manually assigned IDs.