SQLExplorer: Error parsing time

SQLite

I could not find any mention of this error with SQL Explorer (http://eclipsesql.sourceforge.net/)
but in some circumstances when using a DATETIME field - you can end up with an "Error parsing date" like this:

And it is not an issue with the SQLite driver (https://bitbucket.org/xerial/sqlite-jdbc/downloads/)

Assuming you have a table TEST:

CREATE TABLE TEST(TEST_ID INTEGER PRIMARY KEY AUTOINCREMENT,TEST_TIME DATETIME default "datetime('now')",TEST_LOG TEXT) ;

where you can add records like these:

insert into TEST (TEST_LOG) values ("TEST DATE ERROR PARSING")

If you attempt to do a simple select - you will get the error "error parsing date":

select TEST_ID, TEST_TIME TEST_DATE, TEST_LOG from TEST;

This command is perfectly valid under SQLite, or dBeaver, or another SQL client front end - but SQL Explorer (on Windows) may return this error parsing date.

Workaround

Now the workarounds:

select TEST_ID, strftime("%Y-%m-%d %H:%M:%S", TEST_TIME) TEST_DATE, TEST_LOG from TEST;

Another option is to use:

select TEST_ID, datetime(TEST_TIME) TEST_DATE , TEST_LOG from TEST;

SQLite: Loop simplified

As I was discussing this last tip using a simile loop in SQLite to populate data entry http://blogmymix.blogspot.com/2017/06/sqlite-using-table-to-loop.html

A comment was made that the tRange table was not absolutely necessary
as the following command would suffice:

insert into tTarget(i)  select ('My test without tRange: ' || tIndex.id)  from tIndex where tIndex.id <=10000 ;

or with proper formatting

insert into tTarget(i)  
  select ('My test without tRange: ' || tIndex.id)  
  from tIndex where tIndex.id <=10000 ;

SQLite: Using a table to loop

Loop

You want to create a table with lots of records for testing purposes - in SQL you could make a loop using something like this:

while (@i <= 10000)
 begin
  insert into table1 values ( 'field1' + cast (@i as char).
 'field2'+ cast (@i as char).
...
)
set @i+=1
end
go

Unfortunately in SQlite loops are not implemented - but you could use this trick instead
It will use a tIndex table, and a tRange table to generate some records in a tTarget table.

The tTarget table  is for the result:
create table target (i text);

This table will receive the result as text

tRange table

create table tRange (start, finish);
insert into tRange (1, 100) ;

And then afterward you can change the start and finish parameters using:
update tRange set start = 3 ;
update tRange set finish = 90 ;

tIndex table

This one is tricky because it has to contain as many records as possible - you will have to create this table via a Java program (see previous post) - by default there will be 10,000 records.

Now the Loop trick 

insert into tTarget(i)
select ('Record number '||tIndex.id)
from tIndex join tRange
on (tIndex.id >= tRange.start and tIndex.id <= tRange.finish) ;

This will generate Record Number + start ...  up to Record Number+ finish

Java: Creating a table with 10,000 records in SQLite

SQLite: showing a random record from a table

Random record

If many occasion developer want to get a random record(s) from a table, because they are programming a quizz, or a game - it turns out there is no native instructions for that in SQLite
but you can use this workaround:

SELECT
*, random() as R
FROM Table
ORDER BY R
LIMIT 1 ;

Why it works

It insert a random number (R) for each record and then using the order by there is going to be a selection of the smaller number (R)  - you can even change the LIMIT to get more than one record - let say 3

SELECT *, random() as R FROM Table ORDER BY R LIMIT 3 ;

Sqlite: Using auto_increment and current date and time

The idea

As a good tip to get the most of the table entries - you want the user to focus on their important data - but you don't want to overwhelm them with extra typing that can be done automatically by database system.

Here is way to have an auto increment index and a default date and time of the entry done by the operator

Embedded during the table creation: 

sqlite> create table testauto (autoid integer primary key autoincrement, autodate default (datetime('now')), notes text ) ;

Operator just have to enter the notes column: 

sqlite> insert into testauto (notes) values ('this is a test of the auto increment and default date' ) ;
sqlite> insert into testauto (notes) values ('this is a second test of the auto increment and default date' ) ;
sqlite> insert into testauto (notes) values ('this is a third test of the auto increment and default date' ) ;

and as you see the index and the date are automatically filled

sqlite> select * from testauto ;
1|2017-03-15 15:34:05|this is a test of the auto increment and default date
2|2017-03-15 15:34:14|this is a second test of the auto increment and default date
3|2017-03-15 15:34:24|this is a third test of the auto increment and default date
sqlite>

Sqlite: how to generate a random number within range 0..99

Random()

The Sqlite random() function will returns a pseudo-random integer between -9223372036854775808 and +9223372036854775807.

abs() will returns the absolute value of the numeric argument

floor() or round() will return a floating-point value X rounded to Y digits to the right of the decimal point. If the Y argument is omitted, it is assumed to be 0.

NB:floor() will only work within SQLExplorer, Dbeaver, ...

Result

select floor(abs(random()/92233720368547758.07));
will generate within 0..99

and
select round(abs(random()/92233720368547758.07),0);
will generate within 1..100

Sqlite: how to count words in a field

Assuming a table like this:

create table test (id integer primary key autoincrement, name text);

and values like:

insert into test values (null, "test") ;
insert into test values (null, "word1 word2 word3")  ;
insert into test values (null, "word4 word5 word6")  ;
insert into test values (null, "word7 word8 word9 word10 word11 word11")  ;

here is the result:

select id, name from test

1;test
2;word1 word2 word3
3;word4 word5 word6
4;word7 word8 word9 word10 word11 word12

Counting

Now you want to count the word(s) in the field "name" - here is how to proceed:
select (length(name)-length(replace(name," ","")))+1 as wordcount, name from test

it works because the query is looking for the number of space - a space means a new word is in the field and that is why you need to add 1 to the total.

Sqlite is awesome

Sqlite - how to search a table with a list of terms from another table

Here is a little example of how brilliant Sqlite is :

sqlite> .schema  country
CREATE TABLE country(id integer primary key autoincrement, name text);
sqlite> .schema search
CREATE TABLE search(term text);
sqlite> select * from country ;
id|name
1|France
2|Czech Republic
3|Italy
4|Great Britain
5|Ireland
6|Slovakia
7|Senegal
sqlite> select * from search ;
term
%fr%
%cz%
%ir%
ai
sqlite> select a.name from country a join search b on a.name like "%"||b.term||"%" ;
name
France
Czech Republic
Great Britain
Ireland

NB : the || is used for Sqlite for concatenation