I wrote something like
create table if not exists QuickTest (
id integer primary key NOT NULL,
a TEXT DEFAULT #0,
b TEXT,
c TEXT);
I get an error on #0. Is there a way to insert parameters here or do i need to hardcode the value in? I typically like using parameters when setting values.
You have to use string constant or NULL.
http://www.sqlite.org/syntaxdiagrams.html#column-constraint
The DEFAULT constraint specifies a default value to use when doing an INSERT. The value may be NULL, a string constant, a number, or a constant expression enclosed in parentheses. The default value may also be one of the special case-independant keywords CURRENT_TIME, CURRENT_DATE or CURRENT_TIMESTAMP. If the value is NULL, a string constant or number, it is inserted into the column whenever an INSERT statement that does not specify a value for the column is executed. If the value is CURRENT_TIME, CURRENT_DATE or CURRENT_TIMESTAMP, then the current UTC date and/or time is inserted into the columns. For CURRENT_TIME, the format is HH:MM:SS. For CURRENT_DATE, YYYY-MM-DD. The format for CURRENT_TIMESTAMP is "YYYY-MM-DD HH:MM:SS".
You can't use parameters in a ddl (data definition language) statement, only in dml (data manipulation language) statement and select statements are parameters allowed.
CREATE TABLE test (id INTEGER DEFAULT -1, name VARCHAR DEFAULT na)
Above sql will create a table test with two colums id and name
While executing insert for this table if no values are specified for id and name then it will insert -1 for id column and na will be inserted for name column
Related
After creating an sqlite table with a generated column in it, the type only shows up, if it was specified, and there can be cases when junk gets into the type description as well.
Example:
create table test(
id integer primary key not null,
gen generated always as (id * 2) stored
);
Using pragma table_xinfo(test); afterwards nets the following output:
0|id|INTEGER|1||1|0
1|gen||0||0|3
The type is simply missing from the correct column.
If the column were to be created with:
gen integer generated always as (id * 2) stored
instead, then the type would correctly show up as INTEGER.
Are there any methods that would get the type of a column in a table without having to resort to parsing the table creation code?
Nevermind, as usual, I find the answer right after asking it. According to sqlite documentation:
The datatype and collating sequence of the generated column are determined only by the datatype and COLLATE clause on the column definition. The datatype and collating sequence of the GENERATED ALWAYS AS expression have no affect on the datatype and collating sequence of the column itself.
Which I assume means, that just as in other places, if the datatype is not specified, it is thought of as a blob.
I'm trying to create table with default primary key (not autoincrement), similar with oracle
fk_id varchar2(32) default sys_guid()
so table definition is
CREATE TABLE `t_table` (
`fk_id` TEXT DEFAULT 'select lower(hex(randomblob(16)))' UNIQUE,
`fv_name` TEXT,
PRIMARY KEY(`fk_id`)
);
and yes, i'm getting this select as string value while inserting.
so is there any solution without using triggers?
thank you.
Using 'select lower(hex(randomblob(16)))' is enclosing the subquery as a string/text literal and will work only once as UNIQUE has been specified (no need as making the column PRIMARY KEY implies UNIQUE) thus any subsequent inserts would fail.
Assuming that you want the DEFAULT value to be the result of the of lower(hex(randomblob(16)) then you cannot use a subquery as the value is then not considered as a CONSTANT.
For the purposes of the DEFAULT clause, an expression is considered
constant if it contains no sub-queries, column or table references,
bound parameters, or string literals enclosed in double-quotes instead
of single-quotes.SQL As Understood By SQLite - CREATE TABLE
Instead you could remove the select and just use the expression, which is then considered CONSTANT.
However, to do so, you need to adhere to
If the default value of a column is an expression in parentheses, then
the expression is evaluated once for each row inserted and the results
used in the new row. SQL As Understood By SQLite - CREATE TABLE
Thus you could use :-
CREATE TABLE IF NOT EXISTS `t_table` (
`fk_id` TEXT DEFAULT (lower(hex(randomblob(16)))) UNIQUE,
`fv_name` TEXT,
PRIMARY KEY(`fk_id`)
);
Of course should the value not be unique, which would be increasingly likely, then this would result in the row not being inserted.
I am trying to create a table in SQLite with blob type column (Content):
create table [Files]
(
Id int identity not null
constraint PK_File_Id primary key,
MimeType nvarchar (400) not null,
Content varbinary (max) null
constraint DF_File_Content default (0x),
);
However the following is not being accepted:
Content varbinary (max) null
constraint DF_File_Content default (0x),
Why?
"Max" is the name of a standard SQLite3 function, so is not available as part of a type name.
See the syntax reference for the CREATE TABLE statement and data types. A type name can include numbers in parentheses (which are ignored), but not the word “MAX”.
It looks like you're trying to use MS SQL Server syntax, and there are several errors in your code:
As mentioned above, (max) is not accepted as part of a type name. Since value lengths are unconstrained by default, simply omit it.
varbinary gives the column “numeric affinity”. While such a column can store a blob, you'll probably want to declare it as blob instead.
0x is not a valid blob literal. The correct way to write an empty blob is x''.
identity is called autoincrement. And in order to use it, the type name must be integer rather than int. The not null is redundant: If you try to insert a null value into such a column, you'll get the auto-incremented ROWID instead.
Note: If you simply need Id to have unique values at any given time and don't care if previously-deleted values get re-used, then you can simply declare the column as integer primary key, and inserting null will fill in the column with an unused integer. The autoincrement keyword prevents the re-use of ROWIDs over the lifetime of the database, more closely matching the semantics of MS SQL's identity keyword. See the discussion at the link above.
While it's syntactically legal to declare a name for a column constraint, it's not necessary.
Try this:
create table [Files]
(
Id integer primary key autoincrement,
MimeType nvarchar (400) not null,
Content blob null default (x'')
);
Note that this does not enforce a length limit on a MimeType column. If you need to, add the constraint check (length(MimeType) <= 400).
I want to set default value for a varchar column in sqlite.
default value is a path like c:\log
but sqliteStudio don't allow me to add this and after C value rest of values
are in purple:
c:\log
how should I add this?
In SQL, string values must be quoted:
'c:\log'
I am attempting to insert a row into a table while leaving two datetime columns null.
Error (for both columns):
The column column_name in table conflict does not allow null values.
The only constraint the table table has is a primary key constraint. The constraint is not on the datetime columns.
Is it possible to have a null datetime in Sybase?
You could try casting the NULL value as a datetime datatype and see if that works.
For example:
INSERT INTO tbl_conflict (date_column) VALUES (CAST(NULL AS datetime))
I did not realize that Sybase defaulted columns to not null. I need to set the columns as null.