How does one prepare a statement from the SQLite CLI? I have found the page Compiling An SQL Statement but it is geared more towards the ODBC interface, not the CLI interpreter. I'm hopinpg for something akin to the following:
sqlite> pq = prepare(SELECT * FROM Users WHERE username=?)
sqlite> run(pq, 'jeffatwood')
0 | jeffatwood | hunter2 | admin
sqlite>
Does the SQLite CLI have any such functionality? Note that I am not referring to the Bash CLI but rather SQLite's CLI interpreter or the excellent LiteCLI alternative.
Perhaps SQL Parameters using named parameters would do the trick
sqlite> .param set :user 'jeffatwood'
sqlite> select * from Users where username = :user
should return the desired row.
CLI was not designed for such. For this you must use an SQLite API on an available programming language.
You may also write a batch/shell file to handle CLI call.
E.g., in Windows a file named User.bat like following:
#SQLITE3.EXE some.db "SELECT * FROM Users WHERE username='%~1'"
May be called like this:
User "jeffatwood"
will perform desired result.
EDIT:
About prepared/compiled statements: with those you can bind parameters, fetch queries row by row and repeat same command in a faster manner.
sqlite3 CLI tool wouldn't take any advantage on those:
all parameters must be typed in SQL statement, making binding useless;
all query rows are returned at once, no need to fetch row by row;
repeated commands must be retyped - small speed improvement would result in using precompiled statements.
Related
I'm developing a Rust application for user registration via SSH (like the one working for SDF).
I'm using the SQLite3 database as a backend to store the information about users.
I'm opening the database file (or creating it if it does not exist) but I don't know the approach for checking if the necessary tables with expected structure are present in the database.
I tried to use PRAGMA schema_version for versioning purposes, but this approach is unreliable.
I found that there are posts with answers that are heavily related to my question:
How to list the tables in a SQLite database file that was opened with ATTACH?
How do I retrieve all the tables from database? (Android, SQLite)
How do I check in SQLite whether a table exists?
I'm opening the database file (or creating it if it does not exist)
but I don't know the approach for checking if the necessary tables
I found querying sqlite_master to check for tables, indexes, triggers and views and for columns using PRAGMA table_info(the_table_name) to check for columns.
e.g. the following would allow you to get the core basic information and to then be able to process it with relative ease (just for tables for demonstration):-
SELECT name, sql FROM sqlite_master WHERE type = 'table' AND name LIKE 'my%';
with expected structure
PRAGMA table_info(mytable);
The first results in (for example) :-
Whilst the second results in (for mytable) :-
Note that type is blank/null for all columns as the SQL to create the table doesn't specify column types.
If you are using SQLite 3.16.0 or greater then you could use PRAGMA Functions (e.g. pragma_table_info(table_name)) rather than the two step approach need prior to 3.16.0.
I would like to load text from a field in a SQLite table and run it as a SQLite query. All done in a SQLite query. No external string operations, nor command line operations are possible. Pure SQLite only.
Let's say that I would create a table command_table with the rows:
COMMAND_NAME: COMMAND:
command1 SELECT * FROM table1
command2 SELECT * FROM table1 WHERE table1.row1 = '1'
The desired SQLite command would be able to load the COMMAND and interpret it.
The commands would be as complex as it gets, so using some generic comparisons like WHERE table1.row1 = command_table.command1" is not an option.
SQLite is designed as an embedded database, i.e., to be used together with a 'real' programming language. Therefore, it does not have any mechanism to execute dynamic SQL statements from within SQL itself.
The only thing I don't have an automated tool for when working with Oracle is a program that can create INSERT INTO scripts.
I don't desperately need it so I'm not going to spend money on it. I'm just wondering if there is anything out there that can be used to generate INSERT INTO scripts given an existing database without spending lots of money.
I've searched through Oracle with no luck in finding such a feature.
It exists in PL/SQL Developer, but errors for BLOB fields.
Oracle's free SQL Developer will do this:
http://www.oracle.com/technetwork/developer-tools/sql-developer/overview/index.html
You just find your table, right-click on it and choose Export Data->Insert
This will give you a file with your insert statements. You can also export the data in SQL Loader format as well.
You can do that in PL/SQL Developer v10.
1. Click on Table that you want to generate script for.
2. Click Export data.
3. Check if table is selected that you want to export data for.
4. Click on SQL inserts tab.
5. Add where clause if you don't need the whole table.
6. Select file where you will find your SQL script.
7. Click export.
Use a SQL function (I'm the author):
https://github.com/teopost/oracle-scripts/blob/master/fn_gen_inserts.sql
Usage:
select fn_gen_inserts('select * from tablename', 'p_new_owner_name', 'p_new_table_name')
from dual;
where:
p_sql – dynamic query which will be used to export metadata rows
p_new_owner_name – owner name which will be used for generated INSERT
p_new_table_name – table name which will be used for generated INSERT
p_sql in this sample is 'select * from tablename'
You can find original source code here:
http://dbaora.com/oracle-generate-rows-as-insert-statements-from-table-view-using-plsql/
Ashish Kumar's script generates individually usable insert statements instead of a SQL block, but supports fewer datatypes.
I have been searching for a solution for this and found it today. Here is how you can do it.
Open Oracle SQL Developer Query Builder
Run the query
Right click on result set and export
http://i.stack.imgur.com/lJp9P.png
You might execute something like this in the database:
select "insert into targettable(field1, field2, ...) values(" || field1 || ", " || field2 || ... || ");"
from targettable;
Something more sophisticated is here.
If you have an empty table the Export method won't work. As a workaround. I used the Table View of Oracle SQL Developer. and clicked on Columns. Sorted by Nullable so NO was on top. And then selected these non nullable values using shift + select for the range.
This allowed me to do one base insert. So that Export could prepare a proper all columns insert.
If you have to load a lot of data into tables on a regular basis, check out SQL Loader or external tables. Should be much faster than individual Inserts.
You can also use MyGeneration (free tool) to write your own sql generated scripts. There is a "insert into" script for SQL Server included in MyGeneration, which can be easily changed to run under Oracle.
Is there a way to get system/environment variables with SQLite?
I know that by using sqlite3's command line I can do something like:
sqlite> .shell echo $USER
But I want to know if I can implement this in a SQL trigger.
We have multiple users using a shared sqlite database and I want to create an automatic log that records who made that changes to specific tables.
SQLite does not know anything about environment variables. (Many systems on which it runs do not even have them.)
The easiest way to get a user name into a trigger would be to create a user-defined function, but then the trigger would fail if used outside a program that has registered this function.
I am using an Oracle data pump to do a schema "rename." There is a primary key column on all (2000) tables. For example, I need to run this on all tables:
update mytable set mykey='foo2' where mykey='foo';
I would use the remap_data option of expdp to do this. The problem is that there are some columns that I would need to do the rename on 10+ columns. Has anyone had a problem like this and found a way to handle this?
Previously, I had tried using "Create Table As." The problem would be having to recreate the schema structure for all of the tables (views/triggers/grants/indexes/constraints). I am aware of the DBMS_METADATA.GET_DDL package. Offhand, doing a diff of the database schema before and after and recreating the diffs seems ugly.
I have also tried doing inserts on the table without any constraints or indexes, so I would only have to re-enable constraints and recreate the indexes, but I would like to try something faster.
I am using Oracle 11.2.0.3.0.
If i understand correctly, your real problem (or goal) is to 'RENAME' a schema.
You chose to export / import (using a different NAME to achieve RENAME) using oracle data pump.
Then DROP old schema (if you feel redundant).
If this is correct, here are the steps, you can do to achieve your goal. I did it successfully on my DEV env. All objects (including PK, FKs) were imported successfully.
-- Export RMCORE_QA
expdp DIRECTORY=DMPDIR DUMPFILE=RMCORE_QA.dmp SCHEMAS='RMCORE_QA' LOG=RMCORE_QA_EXP_DP.lst
-- Import using RMCORE_QA3
impdp DIRECTORY=DMPDIR DUMPFILE=RMCORE_QA.dmp REMAP_SCHEMA='RMCORE_QA:RMCORE_QA3' SCHEMAS='RMCORE_QA' LOG=RMCORE_QA_IMP_DP.lst TRANSFORM=OID:N
You can also compare objects b/w schemas by-
SELECT OBJECT_NAME, STATUS, object_type FROM dba_objects WHERE owner LIKE 'RMCORE_QA'
MINUS
select OBJECT_NAME, STATUS, object_type from dba_objects where owner like 'RMCORE_QA3';
HTH. Let me know if i did not get your problem...