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| − | See also:
| + | Siehe [https://wiki.hsr.ch/Datenbanken/wiki.cgi?PostgreSQLForMySQLUsers HSR-Datenbanken-Wiki]. |
| − | * [[PostgreSQL]]
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| − | | |
| − | Licensing:
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| − | * MySQL: Dual Licensed
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| − | * PostgreSQL: BSD-Style
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| − | | |
| − | == Internet Resources ==
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| − | | |
| − | * [https://wiki.postgresql.org/wiki/Things_to_find_out_about_when_moving_from_MySQL_to_PostgreSQL Things to find out about when moving from MySQL to PostgreSQL] (PostgreSQL wiki)
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| − | * [https://opslife.org/postgresql-for-mysql-administrators/ PostgreSQL for MySQL Administrators] (opslife blog)
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| − | * [http://www.coderholic.com/postgresql-for-mysql-users/ PostgreSQL for MySQL users] (coderholic blog)
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| − | * [http://stackoverflow.com/questions/772111/switching-from-mysql-to-postgresql-tips-tricks-and-gotchas Switching from MySQL to PostgreSQL - tips, tricks and gotchas?] on StackOverflow
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| − | | |
| − | == MySQL's <code>INSERT UPDATE</code> ==
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| − | Option 1) Write a function like:
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| − | CREATE FUNCTION doinsert(_id integer, _value text) RETURNS void AS $$
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| − | BEGIN
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| − | UPDATE thetable SET value = _value WHERE id = _id;
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| − | IF NOT FOUND THEN
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| − | INSERT INTO thetable(id, value) VALUES (_id, _value);
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| − | END IF
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| − | END;
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| − | $$ LANGUAGE plpgsql;
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| − | | |
| − | Option 2) Use two SQL statements:
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| − | -- update the existing
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| − | UPDATE realTable SET VALUE = (SELECT VALUE FROM tmp WHERE tmp.id = realTable.id)
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| − | WHERE EXISTS (SELECT VALUE FROM tmp WHERE tmp.id = realTable.id);
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| − | -- insert the missing
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| − | INSERT INTO realTable(id, value)
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| − | SELECT id, value FROM tmp WHERE NOT EXISTS(SELECT 1 FROM realTable WHERE tmp.id = realTable.id);
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| − | | |
| − | == MySQL's <code>AUTO INCREMENT</code> ==
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| − | * Oracle: <code>SEQUENCE</code>
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| − | * MySQL: <code>id INT UNSIGNED NOT NULL AUTO_INCREMENT</code>
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| − | * PostgreSQL: <code>id SERIAL</code> oder <code>SEQUENCE</code>
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| − | | |
| − | === Syntactic sugar: <code>SERIAL</code> ===
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| − | CREATE TABLE table_name (
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| − | Identifier SERIAL,
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| − | -- ...
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| − | );
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| − | | |
| − | === The Explicit Way: <code>SEQUENCE</code> ===
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| − | ==== <code>SEQUENCE</code>-Definition ====
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| − | CREATE SEQUENCE myseq;
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| − | ==== <code>SEQUENCE</code>-Usage ====
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| − | '''either''' as the column's default value:
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| − | CREATE TABLE table_name (
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| − | Identifier NUMBER DEFAULT nextval('myseq'),
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| − | -- ...
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| − | );
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| − | '''or''' explicitly each time you insert a new row:
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| − | INSERT ... INTO table_name VALUES(nextval('myseq'), 'Name', ...);
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| − | | |
| − | * See also [https://www.postgresql.org/docs/current/static/datatype-numeric.html#DATATYPE-SERIAL Serial Types] in the PostgreSQL documentation
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| − | | |
| − | == MySQL's <code>INT UNSIGNED</code> (Cardinal) ==
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| − | * MySQL: <code>column INT UNSIGNED</code>
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| − | * PostgreSQL: <code>column INT CHECK (column > 0)</code>
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| − | | |
| − | == MySQL's Index Type ==
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| − | * MySQL: <code>INDEX idx_id(id)</code>
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| − | * PostgreSQL: <code>CREATE INDEX idx_id ON TABLENAME(id);</code>
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| − | | |
| − | == MySQL's Query Resultset Limit ==
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| − | * MySQL: <code>SELECT * FROM tbl LIMIT 10, 5</code>
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| − | * PostgreSQL: <code>SELECT * FROM tbl LIMIT 5 OFFSET 10</code>
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| − | | |
| − | == Data types of MySQL versus PostgreSQL ==
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| − | | |
| − | {| class="mw-datatable"
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| − | |-
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| − | ! colspan=2 | Mysql !! colspan=2 | PostgreSQL!!
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| − | |-
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| − | ! Typ !! Beschreibung !! Typ !! Beschreibung
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| − | |-
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| − | | tinyint || -128..127 || - || -
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| − | |-
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| − | | smallint || -32768..+32767 || int2 || -32767 ... +32768
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| − | |-
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| − | | int || -2147483648.. +2147483647 || int4 || -2147483648 ... +2147483647
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| − | |-
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| − | | || || int8 || +/- 18 Dezimalstellen
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| − | |-
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| − | | float(n) || n E {4;8}, Einf./doppelte Genauig.|| float4 || 6 Dez.Stellen
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| − | |-
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| − | | || || float8 || 15 Dezimalstellen
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| − | |-
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| − | | date || YYYY-MM-DD Datumsformat || date || Datum, Datumformate mit SET DATESTYLE=Value einstellbar
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| − | |-
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| − | | time || HH-MM-SS Zeitformat || time || Uhrzeit, Auflösung 1 Mikrosekunde
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| − | |-
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| − | | char(m) || Zeichenkette mit fester Länge || char || ein Zeichen
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| − | |-
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| − | | varchar(m) || variable Länge, max. m Zeichen || varchar(n) || 4+n Bytes
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| − | |-
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| − | | blob || Binary Large Object, wird für Texte gebraucht, "TINY", "", "LONG" || bytea
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| − | |-
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| − | | || || money || 4 Byte, -21474836,48 ... +21474836,47
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| − | |-
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| − | | || || text || Variable Länge
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| − | |-
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| − | | || || bool || Kann den Wert 't' oder 'f' annehmen
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| − | |}
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