I wish to have a table name with
hello [world]
So, I thought using the following syntax would work
create table [hello [world]]] (key INTEGER PRIMARY KEY);
I get
Error: unrecognized token: "]"
I was wondering, is having square bracket supported in SQLite?
There are multiple methods for quoting identifiers.
When using square brackets, it is not possible to have these characters in the identifier.
When using double quotes, you can escape them in the name by doubling them:
CREATE TABLE "hello ""world"""(key INTEGER PRIMARY KEY);
Try quoting the table name:
$ sqlite3 :memory:
sqlite> create table "Foo [bar]" (a int);
sqlite> .schema
CREATE TABLE "Foo [bar]" (a int);
sqlite> insert into "Foo [bar]" values(1);
sqlite> select * from "Foo [bar]";
1
sqlite> _
Related
I create a SQLite function which takes a string and returns another string, then I can use the return value as match strings. Code is here
It works very well except for the single quotes. In this case, it can't match any rows, but if I directly use the returned string, it can match. Anyone know what's the problem here?
sqlite> select simple_query('''');
"''"
sqlite> select ' ', simple_highlight(t1, 0, '[', ']') from t1 where x match simple_query('''');
sqlite> select ' ', simple_highlight(t1, 0, '[', ']') from t1 where x match '"''"';
|#English &special _characters."[']bacon-&and[']-eggs%
Full example here
This question finally answered in sqlite-forum, and I'd like to post the reason in here.
The reason is SQLite will try to escape the string for us, we can verify that after turn on quote mode, as you can see, our return value will be escaped from "'" to "''" by SQLite. Which means we don't need to escape single quote in our function.
sqlite> select simple_query('''');
"'"
sqlite> select simple_query('"');
""""
sqlite> .mode quote
sqlite> select simple_query('"');
'""""'
sqlite> select simple_query('''');
'"''"'
Very similar to How to display blob value using x'abc' binary string literal syntax?:
How can I have the sqlite3 shell display always display blob columns using the hex notation, as per e.g. quote(blob_column_name), without explicitly using quote, and in select * queries (and other contexts where blob_column_name isn't mentioned explicitly)?
(I suspect the answer is "you can't", but I'm hoping to be pleasantly surprised.)
There are two output modes that use SQL syntax (not only for blobs but for all values):
sqlite> .mode quote
sqlite> SELECT 1, x'123ABC', 'hello', null;
1,X'123abc','hello',NULL
sqlite> .mode insert
sqlite> SELECT 1, x'123ABC', 'hello', null;
INSERT INTO "table" VALUES(1,X'123abc','hello',NULL);
When I run sqlite3 foo.db from cmd (Windows) and enter these commands (assuming TABLE 'test' does not exist):
sqlite> CREATE TABLE test (id integer PRIMARY KEY, name char(1));
sqlite> INSERT INTO test (name) VALUES ('aaaaaa');
there are no errors. To verify,
//Input
sqlite> SELECT * FROM test;
//Output
1|aaaaaa
Again, to verify,
sqlite> .schema test
CREATE TABLE test (id integer PRIMARY KEY, name char(1)); //output
and the schema isn't changed.
Is there something wrong, especially with the name char(1) part? For the record, I compiled SQLite3 using MinGW64 with
--host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --prefix=/mingw // where /mingw is included in my PATH
Thanks in advance.
As there is no types in SQLite, the question is meaningless. All TEXT values are the same and are stored as "unlimited" (up to SQLITE_MAX_LENGTH) length strings.
What you see is a WAD: "working as designed".
SQLite doesn't enforce the length of a char(n) or varchar(n) column as it's declared in a CREATE TABLE statement. But you can enforce length restrictions using a CHECK constraint.
sqlite> create table test (
...> id integer primary key,
...> name char(1),
...> check (length(name)<=1)
...> );
sqlite> INSERT INTO test (name) VALUES ('aaaaaa');
Error: CHECK constraint failed: test
How to crate a now row without knowing the any of the columns of the table and using default values therefore?
In sqlite3 I simply do:
sqlite> CREATE TABLE t ("id" INTEGER PRIMARY KEY, "text" TEXT DEFAULT "hello world");
sqlite> INSERT INTO t DEFAULT VALUES;
sqlite> SELECT * FROM t;
1|hello world
But in sqlite2.8.17 I get:
sqlite> INSERT INTO t DEFAULT VALUES;
SQL error near 'DEFAULT': Syntax error.
Is there a way to do this right in sqlite2 or do I need to give the values manually in the insert statement?
You have to specify at least one value; all the others will then get their default values.
The rowid automatically gets a value when you specify NULL, so you can use that one:
INSERT INTO t(id) VALUES(NULL);
Can I create a database constraint on a TEXT column in SQLite disallowing the value of the column to be empty string ""?
I want to allow the column to be null, but disallow empty string.
Yes you can:
sqlite> create table foo (bar TEXT, CHECK(bar <> ''));
sqlite> insert into foo values (NULL);
sqlite> insert into foo values ('bla');
sqlite> insert into foo values ('');
Error: constraint failed
You can use a CHECK constraint (http://www.sqlite.org/lang_createtable.html):
SQLite version 3.5.9
Enter ".help" for instructions
sqlite> create table example(col, CHECK (col is null or length(col) > 0));
sqlite> insert into example values ('');
SQL error: constraint failed
sqlite> insert into example values (null);
sqlite> insert into example values ('sample');
sqlite> .nullvalue NULL
sqlite> select col from example;
NULL
sample
As far as i know doesn't exist a similar constraint in SQLite, but maybe you can workaround with a Trigger that on INSERT and/or UPDATE automatically change the string empty in NULL.